tag:blogger.com,1999:blog-39430566592369458002024-03-13T15:36:03.271-07:00OK7MSMarSikhttp://www.blogger.com/profile/04703143981787504455noreply@blogger.comBlogger11125tag:blogger.com,1999:blog-3943056659236945800.post-43005634992236343502017-04-27T14:51:00.000-07:002017-05-05T01:55:11.770-07:00Using cheap RC522 NFC reader to read Mifare Ultralight C<span style="font-family: "arial" , "helvetica" , sans-serif;"><a href="https://www.mifare.net/en/products/chip-card-ics/mifare-ultralight/mifare-ultralight-c/">Mifare Ultralight C</a> seems to be one of the most overlooked card types when secure cloning prevention is needed. It can only store 192 bytes of information, has just a single key and one counter. But the authentication sequence is the same as what the much more expensive <a href="https://www.mifare.net/en/products/chip-card-ics/mifare-desfire/">DESfire</a> uses. So I realized the commonly used DESfire is an overkill when I started looking into why single purpose autonomous building access systems are so expensive.</span><br />
<span style="font-family: "arial" , "helvetica" , sans-serif;"><br /></span>
<span style="font-family: "arial" , "helvetica" , sans-serif;">Just compare the prices (TME, VAT not included):</span><br />
<span style="font-family: "arial" , "helvetica" , sans-serif;"><br /></span>
<span style="font-family: "arial" , "helvetica" , sans-serif;"><a href="http://www.tme.eu/cz/details/rfid-gw-desfire-2k/moduly-rfid/goodwin/mifare-desfire-2k-iso-pvc-white-card-th/">DESfire 2k</a> - 0.96€ (<i>100pcs</i>)</span><br />
<span style="font-family: "arial" , "helvetica" , sans-serif;"><a href="http://www.tme.eu/en/details/rfid-gw-desfire-4k/rfid-modules/goodwin/mifare-desfire-4k-iso-pvc-white-c-therm/">DESfire 4k</a> - 1.09€ (<i>100pcs</i>)</span><br />
<span style="font-family: "arial" , "helvetica" , sans-serif;"><a href="http://www.tme.eu/cz/details/rfid-gw-ultra-c/moduly-rfid/goodwin/pvc-white-card-ultralight-c/">Ultralight C</a> - 0.31€ (<i>100pcs</i>)</span><br />
<span style="font-family: "arial" , "helvetica" , sans-serif;"><br /></span>
<span style="font-family: "arial" , "helvetica" , sans-serif;">Plain Ultralight is even cheaper, but does not have any security at all (just couple of write once bits):</span><br />
<span style="font-family: "arial" , "helvetica" , sans-serif;"><br /></span>
<span style="font-family: "arial" , "helvetica" , sans-serif;"><a href="http://www.tme.eu/en/details/rfid-gw-ultralight/rfid-modules/goodwin/pvc-white-card-ultralight-ev1/">Ultralight EV1</a> - 0.24€ (<i>100pcs</i>)</span><br />
<span style="font-family: "arial" , "helvetica" , sans-serif;"><a href="http://www.tme.eu/en/details/rfid-gw-ntag213/rfid-modules/goodwin/pvc-white-card-ntag213-thermal-sn/">NTAG213</a> - 0.23€ (<i>100pcs</i>)</span><br />
<span style="font-family: "arial" , "helvetica" , sans-serif;"><br /></span>
<span style="font-family: "arial" , "helvetica" , sans-serif;">I will add <a href="https://www.mifare.net/en/products/chip-card-ics/mifare-classic/">Mifare Classic</a> pricing here as well, but remember the <a href="https://en.wikipedia.org/wiki/MIFARE#Security_of_MIFARE_Classic.2C_MIFARE_DESFire_and_MIFARE_Ultralight">authentication there was broken about ten years ago</a> so it can be also considered to be plain data storage medium only. It is not possible to prevent cloning, however there are systems that can detect cloned cards using a combination of ever increasing counter and a cryptographic signature (see for example <a href="http://www.avoine.net/rfid/download/papers/LehtonenOIM-2009-pervasive.pdf">here</a> or <a href="http://proxmark.nl/files/Documents/13.56%20MHz%20-%20MIFARE%20Classic/Making.the.Best.of.Mifare.Classic-manuscript.2008.pdf">here</a>).</span><br />
<span style="font-family: "arial" , "helvetica" , sans-serif;"><br /></span>
<span style="font-family: "arial" , "helvetica" , sans-serif;"><a href="http://www.tme.eu/cz/details/rfid-gw-mifare-1k/moduly-rfid/goodwin/pvc-white-card-mifare-1k-with-thermal-uv/">Mifare 1k</a> - 0.18€ (<i>100pcs</i>)</span><br />
<span style="font-family: "arial" , "helvetica" , sans-serif;"><a href="http://www.tme.eu/cz/details/rfid-gw-mifare-ev1/moduly-rfid/goodwin/pvc-white-card-mifare-ev1-1k/">Mifare 1k EV1</a> - 0.54€ (<i>100pcs</i>)</span><br />
<span style="font-family: "arial" , "helvetica" , sans-serif;"><br /></span>
<span style="font-family: "arial" , "helvetica" , sans-serif;">So here we have the Ultralight C card that is still secure and costs one third of the commonly used DESfire when cloning prevention is a priority.</span><br />
<span style="font-family: "arial" , "helvetica" , sans-serif;"><br /></span>
<span style="font-family: "arial" , "helvetica" , sans-serif;">An ideal candidate for a research project. Now, what about cheap reader/writer devices? There we have couple of popular options:</span><br />
<ul>
<li>NFC enabled Android phone <b>(A)</b></li>
<li><a href="http://www.nxp.com/products/identification-and-security/nfc-and-reader-ics/nfc-controller-solutions/nfc-integrated-solution:PN5321A3HN" style="font-family: Arial, Helvetica, sans-serif;">PN532</a><span style="font-family: "arial" , "helvetica" , sans-serif;"> based</span><span style="font-family: "arial" , "helvetica" , sans-serif;"> devices</span></li>
<ul>
<li>Adafruit <b>(B)</b></li>
<li>Elechouse <b>(C)</b> and its clones <b>(D)</b></li>
</ul>
<li><span style="font-family: "arial" , "helvetica" , sans-serif;">anonymous</span> "<i><span style="font-family: "arial" , "helvetica" , sans-serif;">Chinese</span></i>" <a href="http://www.nxp.com/products/identification-and-security/nfc-and-reader-ics/nfc-frontend-solutions/standard-performance-mifare-and-ntag-frontend:MFRC52202HN1" style="font-family: Arial, Helvetica, sans-serif;">RC522</a><span style="font-family: "arial" , "helvetica" , sans-serif;"> based devices <b>(E)</b></span></li>
</ul>
<br />
<span style="font-family: "arial" , "helvetica" , sans-serif;">All should be able to communicate with the card according to the chip datasheets. I ordered all the readers mentioned above and did some compatiblity tests with them. And the reality was a bit more interesting than expected indeed.</span><br />
<span style="font-family: "arial" , "helvetica" , sans-serif;"><br /></span>
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgeMNgZhC1E8HrhqdvyERkHNZionhJvXn8jwsb0_gq3XjT1iMdsvZVcLhwfCDLnQ-gLpOmGtFENF9S2rNnfd6_FeKnohUAkL_Dkdlkq3DskHzXgPqJh4lJCLXJEEpq2zAimh5CEeKdetxTT/s1600/cards.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgeMNgZhC1E8HrhqdvyERkHNZionhJvXn8jwsb0_gq3XjT1iMdsvZVcLhwfCDLnQ-gLpOmGtFENF9S2rNnfd6_FeKnohUAkL_Dkdlkq3DskHzXgPqJh4lJCLXJEEpq2zAimh5CEeKdetxTT/s320/cards.JPG" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Some of the cards and tokens used for the tests</td></tr>
</tbody></table>
<span style="font-family: "arial" , "helvetica" , sans-serif;"><br /></span>
<br />
<span style="font-family: "arial" , "helvetica" , sans-serif;"><b>(A)</b> My old <a href="https://en.wikipedia.org/wiki/Samsung_Galaxy_Ace_2">Samsung Galaxy Ace 2 (i8160p) </a>was able to talk to all the cards I have available (Mifare 1k and its clones, Ultralight C, DESfire and DESfire EV1). So I used it as a reference reader for my tests.</span><br />
<br />
<span style="font-family: "arial" , "helvetica" , sans-serif;"><br /></span>
<span style="font-family: "arial" , "helvetica" , sans-serif;"><b>(B)</b> <a href="https://www.adafruit.com/product/789">Adafruit PN532 Arduino</a> shield. PN532 is a high level chip that does all the basic <a href="https://en.wikipedia.org/wiki/ISO/IEC_14443">ISO 14443</a>-3 handling by itself and the application only needs to implement the card specific protocol. </span><span style="font-family: "arial" , "helvetica" , sans-serif;">This is really well designed board that uses the chip and it reads all cards I have with no issues as expected. It is also the most expensive board in the test.</span><br />
<span style="font-family: "arial" , "helvetica" , sans-serif;"><br /></span>
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgbDipRjmDZIj6lgEtc5ZTkJXSgplDnsSeG_sSQmpayBgFBmHBCeuRWg5YLUlY3JCZflCplWw3pFxgH5FF5bct8hz9IAJHwTl9864wSwLGB3G_B8UjQNXQUlyomUm_XsXCyQ-RMpVo_7gMs/s1600/Adafruit-PN532.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="210" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgbDipRjmDZIj6lgEtc5ZTkJXSgplDnsSeG_sSQmpayBgFBmHBCeuRWg5YLUlY3JCZflCplWw3pFxgH5FF5bct8hz9IAJHwTl9864wSwLGB3G_B8UjQNXQUlyomUm_XsXCyQ-RMpVo_7gMs/s400/Adafruit-PN532.JPG" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Adafruit PN532 Arduino shield in UART mode<br />
connected to BusPirate</td></tr>
</tbody></table>
<span style="font-family: "arial" , "helvetica" , sans-serif;"><br /></span>
<span style="font-family: "arial" , "helvetica" , sans-serif;"><br /></span>
<span style="font-family: "arial" , "helvetica" , sans-serif;"><b>(C)</b> <a href="http://www.elechouse.com/elechouse/index.php?main_page=product_info&cPath=90_93&products_id=2242">Elechouse PN532 module V3</a>. There are reports that it really is different from all its clones and should work properly with all Mifare cards. It is also PN532 based so the notes from the Adafruit board (B) apply as well. My tests confirm that. I had no issues reading DESfire and Ultralight C cards.</span><br />
<span style="font-family: "arial" , "helvetica" , sans-serif;"><br /></span>
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg33cVKVtGTxg5nJUHkOarGeCklzgpWT2ixgpOmowJs0JWAlTaiJpuUWXi7AY55dKwSkLJbKgyjIpsblmSIuGhjeSYyDnhkSQZUCcA1VI-m8t_QO5N_h4y7O6w9I0Bnjz7vyP-V4OjvnStG/s1600/IMG_0061.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg33cVKVtGTxg5nJUHkOarGeCklzgpWT2ixgpOmowJs0JWAlTaiJpuUWXi7AY55dKwSkLJbKgyjIpsblmSIuGhjeSYyDnhkSQZUCcA1VI-m8t_QO5N_h4y7O6w9I0Bnjz7vyP-V4OjvnStG/s1600/IMG_0061.jpg" /></a></td><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg_qUIJ14qEuTKCauV5g2eccUrs_f16bv8rLmZNgKFQHvRx785I7A57dXtoxZ0-wXMNZLv1mACYeCkHDdBgpzQhwJN0n-VYUkrvNRki4sSTXJMkXDv5BXNDi5z3ksxcavMIO7DAftliGt9p/s1600/IMG_0062.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg_qUIJ14qEuTKCauV5g2eccUrs_f16bv8rLmZNgKFQHvRx785I7A57dXtoxZ0-wXMNZLv1mACYeCkHDdBgpzQhwJN0n-VYUkrvNRki4sSTXJMkXDv5BXNDi5z3ksxcavMIO7DAftliGt9p/s1600/IMG_0062.jpg" style="cursor: move;" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">original Elechouse PN532 (notice the font used<br />
for <span style="font-size: 12.8px;">mode table at the lower left corner)</span></td><td class="tr-caption" style="text-align: center;">Back side of original Elechouse PN532, notice<br />
the Elechouse name IS printed in italic and top edge<br />
signal names have names</td></tr>
</tbody></table>
<span style="font-family: "arial" , "helvetica" , sans-serif;"><br /></span>
<span style="font-family: "arial" , "helvetica" , sans-serif;"><br /></span>
<span style="font-family: "arial" , "helvetica" , sans-serif;"><b>(D)</b> <a href="https://www.amazon.co.uk/KKmoon-Module-Breakout-Arduino-Android/dp/B01GJX7F9K">Elechouse clone (Kkmoon)</a> detected Mifare cards with 4 byte ID just fine, but it never noticed any card with 7 byte long ID - like DESfire, DESfire EV1 or Ultralight C. <a href="https://forum.nfcring.com/topic/253/elechouse-clone-cooqrobot-pn532-reader-not-recommended">The same was reported for some other clones</a>. I confirmed this behaviour by using both custom hardware (<a href="https://www.codeproject.com/articles/1096861/diy-electronic-rfid-door-lock-with-battery-backup">based on this project</a>) and using <a href="http://nfc-tools.org/index.php?title=Libnfc">libnfc tooling</a>. <a href="https://github.com/nfc-tools/libnfc/issues/352">nfc-tools issue #352</a> also confirms this behaviour.</span><br />
<span style="font-family: "arial" , "helvetica" , sans-serif;"><br /></span>
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj0nvTK1QragirfaaNskv9QDAioT4PunRtuHhe93Un9WI0tEVwFHSxGxg3JEmiY8vna718RvqHp7YNcmBjmL7hGvBNdIy9kS7R9mkSLGyeKWqQxDAUvtgIC16zEegbpNEggkSCi8qpWiHb1/s1600/kkmoon-PN532.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj0nvTK1QragirfaaNskv9QDAioT4PunRtuHhe93Un9WI0tEVwFHSxGxg3JEmiY8vna718RvqHp7YNcmBjmL7hGvBNdIy9kS7R9mkSLGyeKWqQxDAUvtgIC16zEegbpNEggkSCi8qpWiHb1/s320/kkmoon-PN532.JPG" /></a></td><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhan0P1b7DiqsF_7oXUoWLT0sOjL3pNZZJd4xi6Q3nkca5cJuujlA7eLjV-Wi6ICgGGsfTfaASpFaZEpfFzuj4_m1Lbc5zcogdX5qFNoWztGm_hFbLTghDHoP4FKjhOJftwWTp5PiVPIH9u/s1600/kkmoon-PN532-back.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhan0P1b7DiqsF_7oXUoWLT0sOjL3pNZZJd4xi6Q3nkca5cJuujlA7eLjV-Wi6ICgGGsfTfaASpFaZEpfFzuj4_m1Lbc5zcogdX5qFNoWztGm_hFbLTghDHoP4FKjhOJftwWTp5PiVPIH9u/s320/kkmoon-PN532-back.JPG" style="cursor: move;" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">KKmoon PN532 with reset signal wired to the top header</td><td class="tr-caption" style="text-align: center;">Back side of Kkmoon PN532, notice<br />
the Elechouse name is not printed in italic</td></tr>
</tbody></table>
<span style="font-family: "arial" , "helvetica" , sans-serif;"><br /></span>
<br />
<span style="font-family: "arial" , "helvetica" , sans-serif;"><b>(E)</b> The cheapest reader was an RC522 board I bought <a href="https://www.gme.cz/arduino-rfid-ctecka">locally (GMe 772-164)</a>. It was able to read Mifare 1k just fine, it also detected DESfire when the card was almost touching the antenna but it never noticed the Ultralight C card. </span><br />
<span style="font-family: "arial" , "helvetica" , sans-serif;"><br /></span>
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjMk57ApXIcAhUz_Rd_DwW9w0OwnEG-tUGWCUgRZYb6GFpWz_f-BgYTy0YijopcXlb2kkw-zpswwpFA-V9NnV-BjfJr7v-wQGB45VIMXmIy4P1nmeHkDDPMxqY77Rh5iwuuX1XL_4wqNZ_T/s1600/RC522-customized.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="217" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjMk57ApXIcAhUz_Rd_DwW9w0OwnEG-tUGWCUgRZYb6GFpWz_f-BgYTy0YijopcXlb2kkw-zpswwpFA-V9NnV-BjfJr7v-wQGB45VIMXmIy4P1nmeHkDDPMxqY77Rh5iwuuX1XL_4wqNZ_T/s320/RC522-customized.JPG" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">RC522 board with replaced parts and a custom clearance hole</td></tr>
</tbody></table>
<span style="font-family: "arial" , "helvetica" , sans-serif;"><br /></span>
<span style="font-family: "arial" , "helvetica" , sans-serif;">All NFC cards need a certain strength of the electromagnetic field to properly activate. The reading distance using the unmodified board is pretty bad for all cards and Ultralight C can't be powered at all. There are lots of questions on the internet about how to improve the reading distance when using this board. Sadly, answers are either horribly wrong (RC522 can't support 3DES cards), just wrong (can' t read this card type with Arduino Uno), or focused on the software stack only (increase receiver sensitivity using the built in register).</span><br />
<span style="font-family: "arial" , "helvetica" , sans-serif;"><br /></span>
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg-a27M76a-GniBFlSnMB32Ra64G5d2e3MGpc_aa6-uGdKMRbQ4PJscQXgzOyN9Qdeh3ZcGYq2phvHAhDGB8LvGfO61u5qCAU2CBNNb8GSkYkK6Zc7ptJRdgegGMIhSYXeXI54xLEYWGzuT/s1600/RC522-connected.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg-a27M76a-GniBFlSnMB32Ra64G5d2e3MGpc_aa6-uGdKMRbQ4PJscQXgzOyN9Qdeh3ZcGYq2phvHAhDGB8LvGfO61u5qCAU2CBNNb8GSkYkK6Zc7ptJRdgegGMIhSYXeXI54xLEYWGzuT/s320/RC522-connected.JPG" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">RC522 board connected to TI Stellaris Launchpad I just had lying around. It was running a modified<br />
<a href="https://github.com/miguelbalboa/rfid/blob/master/examples/DumpInfo/DumpInfo.ino">https://github.com/miguelbalboa/rfid/blob/master/examples/DumpInfo/DumpInfo.ino</a> sketch</td></tr>
</tbody></table>
<span style="font-family: "arial" , "helvetica" , sans-serif;"><br /></span>
<span style="font-family: "arial" , "helvetica" , sans-serif;">I only needed to realize (and read the datasheet) that the <a href="http://www.nxp.com/products/identification-and-security/nfc-and-reader-ics/nfc-frontend-solutions/standard-performance-mifare-and-ntag-frontend:MFRC52202HN1">RC522</a> chip does not provide any real high level capabilities. It only manages the RF field and does modulation/demodulation of the signal (up to ISO 14443-2). All <a href="https://en.wikipedia.org/wiki/ISO/IEC_14443">ISO 14443</a>-3 collision resolving and higher card protocols have to be done in software. This means the chip can support all cards it can talk to using the supported frequency and modulation and that includes the Ultralight C. So the issue is not there.</span><br />
<span style="font-family: "arial" , "helvetica" , sans-serif;"><br /></span>
<span style="font-family: "arial" , "helvetica" , sans-serif;">It turns out the design of the board is sound, but the component selection is poor and tuning is not perfect. <a href="https://forum.mikroe.com/viewtopic.php?f=147&t=64203">This was discovered</a> by the only single person I have seen in all the forums to investigate the RF design and component selection of that board. <b>Thank you ermok!</b></span><br />
<br />
<span style="font-family: "arial" , "helvetica" , sans-serif;">Now, the fix that is needed to make this board a good performer is supposed to be very simple. There are <a href="https://forum.mikroe.com/download/file.php?id=10892">two inductors</a> on this board that are of the right nominal value (2u2), but are simply unfit when you take a look at their current carrying capability and operating frequency. Replacing them with <a href="http://www.tme.eu/cz/details/cw1008-2200/smd-cipy/ferrocore/">a properly rated inductor</a> increases the current that can flow through the antenna and that increases the generated electromagnetic field which should allow the card to properly power up.</span><br />
<span style="font-family: "arial" , "helvetica" , sans-serif;"><br /></span>
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhf7C4n-at86Ck9CbMdz2NMJoRscLKrATJ9BQhl3wCnxyC7Si8R7w3j9T-tdmC97DTablnrnn54hV2iHpTS0_WA6SQkNSQBgEXHWQVNdLn683ciitwHLycCpXzUoOKViK960qUEnJOrTkuq/s1600/RC522-inductors.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="172" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhf7C4n-at86Ck9CbMdz2NMJoRscLKrATJ9BQhl3wCnxyC7Si8R7w3j9T-tdmC97DTablnrnn54hV2iHpTS0_WA6SQkNSQBgEXHWQVNdLn683ciitwHLycCpXzUoOKViK960qUEnJOrTkuq/s320/RC522-inductors.JPG" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Replaced inductors<br />
(pay no atention to my soldering, I had little time and only crude tools)</td></tr>
</tbody></table>
<span style="font-family: "arial" , "helvetica" , sans-serif;"><br /></span><span style="font-family: "arial" , "helvetica" , sans-serif;">The other change needed seems to be replacing two tuning capacitors (0805 SMD size). Changing the value from 47p to 33p (using <a href="https://en.wikipedia.org/wiki/Ceramic_capacitor">ceramic chip</a> <a href="http://www.avx.com/products/ceramic-capacitors/surface-mount/c0g-np0-dielectric/">C0G</a> capacitor) should improve tuning and that should increase the field strength even more.</span><br />
<span style="font-family: "arial" , "helvetica" , sans-serif;"><br /></span>
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhyfX1eEQlb6p_RSvRb3lbXF5vOE8oJoHs4IvVZd_ioKv1Svf_0xG_FlpjEa6AWl8guBwUNze96hvUiQsqreeVwQdsC4nLwe1ARTwwWQ6ymtrifzJuSxtgDe_FsZhrhcaMucyUeiZtnFHuZ/s1600/RC522-caps.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="172" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhyfX1eEQlb6p_RSvRb3lbXF5vOE8oJoHs4IvVZd_ioKv1Svf_0xG_FlpjEa6AWl8guBwUNze96hvUiQsqreeVwQdsC4nLwe1ARTwwWQ6ymtrifzJuSxtgDe_FsZhrhcaMucyUeiZtnFHuZ/s320/RC522-caps.JPG" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Replaced capacitors (33p 0805 C0G ceramic)</td></tr>
</tbody></table>
<br />
<span style="font-family: "arial" , "helvetica" , sans-serif;">I decided to give it a try since I wanted to use Ultralight C cards and the reader was so cheap (about 8€) so I was not afraid to break it. I ordered the recommended set of inductors (<span class="producer_name" style="box-sizing: border-box;">FERROCORE</span> CW1008-2200 - 1.26€ per <i>10 pcs</i>), used hot air to remove the old parts and soldered the replacements. And guess what.. suddenly the reader recognizes Ultralight C cards just fine. The reading distance is not great, but good enough for the close proximity based access control system reader.</span><br />
<span style="font-family: "arial" , "helvetica" , sans-serif;"><br /></span>
<span style="font-family: "arial" , "helvetica" , sans-serif;">So a simple sub-1€ fix was enough to make this cheap board into a proper and usable reader (and writer). The question now is.. can the same procedure be adapted for the PN532 boards, or is the issue there more substantial (like a counterfeit PN532 chip)?</span>MarSikhttp://www.blogger.com/profile/04703143981787504455noreply@blogger.com8tag:blogger.com,1999:blog-3943056659236945800.post-63496816583021672452014-04-07T11:42:00.003-07:002014-04-08T03:04:44.804-07:00Portable station above 1000m ASL with small transmitting loopI went to <a href="https://www.google.com/maps?q=orlick%C3%A9+hory&hl=en&ie=UTF8&sll=37.0625,-95.677068&sspn=57.161276,79.013672&t=h&z=16&iwloc=A">Orlické hory</a> for the last weekend. That was a great opportunity to test my small transmitting loop antenna. Count in the chance of making my first <a href="http://www.sota.org.uk/">SOTA</a> activation ever and you get a perfect motivation. On the other hand, the main purpose of the trip was a (geocaching) weekend with my family. That always means limited air time.<br />
<br />
The antenna was a small transmitting loop made out of 3 meters of <a href="http://www.ssb.de/pdfs/6060_Aircom%20Plus_en.pdf">Aircom+</a> coax cable. The diameter was about 1m and the tuning capacitor (YO3GGX used the same <a href="http://www.yo3ggx.ro/PortableMagLoopBuild_v1.0.pdf">type</a>) was connected to it using a pair of gold plated N connectors (to make it easily transportable). If there is something familiar about this design it is because it is close to the well known <a href="http://www.alexloop.com/instructions2.html">Alex loop</a>.<br />
<br />
The design spreadsheet with numbers is here (I used <a href="http://www.aa5tb.com/loop.html">AA5TB</a>'s spreadsheet updated to use metric units and converted to <a href="https://www.libreoffice.org/">LibreOffice</a>): <a href="https://dl.dropboxusercontent.com/u/13472947/aa5tb_loop_v1.22a_metric_msloop.ods">aa5tb_loop_v1.22a_metric.ods</a><br />
<br />
Check the simulation on the images here. I did not add any loss resistance so it shows an ideal antenna with the entered proportions. However the connectors add some loss so the real performance is "a bit" worse:<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhniAugx7Co8RKeSEnMGGMc7Yjw8Hbj8_Qr2n8Orx9tMP1Sq1_xSqhGYMqu9ReKvEFnBTrnSnkrfBT3s-601PI0gkuxuefQFO2BpO9VwV6KYdhC9_D7HS6oyRH4sb-ojNUr4A6Gfy8fSC5L/s1600/design-table.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhniAugx7Co8RKeSEnMGGMc7Yjw8Hbj8_Qr2n8Orx9tMP1Sq1_xSqhGYMqu9ReKvEFnBTrnSnkrfBT3s-601PI0gkuxuefQFO2BpO9VwV6KYdhC9_D7HS6oyRH4sb-ojNUr4A6Gfy8fSC5L/s1600/design-table.png" height="353" width="400" /></a></div>
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgBA1YCBlFf83LvYJro0KQuBzJpIr6P7thfMSPUp9ZHpCoOkCX1RETi5hGz4483qSMIDWuYzLrGC7_llPG01mmstzs7vIKXaJJ2Y0s9DceMs9WKqWPAzICfY1xY0r_Av_szlkjRq3IMpTmS/s1600/design-graph.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgBA1YCBlFf83LvYJro0KQuBzJpIr6P7thfMSPUp9ZHpCoOkCX1RETi5hGz4483qSMIDWuYzLrGC7_llPG01mmstzs7vIKXaJJ2Y0s9DceMs9WKqWPAzICfY1xY0r_Av_szlkjRq3IMpTmS/s1600/design-graph.png" height="307" width="400" /></a></div>
<br />
The tuning box consists of the variable capacitor and a <a href="http://www.gme.cz/elektricky-motor-s-prevodovkou-gm25-300chv-286-r-p671-034">motor</a> (5Vdc, 16rpm). The two sections of the capacitor are wired in series and form a split arrangement to double the voltage rating and remove the loss of wiper contacts.<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjjFSkmIfm_amD_EQXALK87ZlpVkjQS1SztG5IWweKrmPVDUY7_rQgbAd6gyq4NOSh0pqFU_VMIFvkOKYeP5SEG15dxxAoRNb2iTgTZuwq1Fn_nIv4pvn7wuYTvbOQBKttk_AaRGzrB1M6d/s1600/20140407_203009.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjjFSkmIfm_amD_EQXALK87ZlpVkjQS1SztG5IWweKrmPVDUY7_rQgbAd6gyq4NOSh0pqFU_VMIFvkOKYeP5SEG15dxxAoRNb2iTgTZuwq1Fn_nIv4pvn7wuYTvbOQBKttk_AaRGzrB1M6d/s1600/20140407_203009.jpg" height="300" width="400" /></a></div>
<br />
<br />
Unfortunately I do not yet have the necessary handles for the axles and so the motor was not utilized in this experiment. The plan is to use a belt and two pulleys of different diameter to make the turning rate even slower.<br />
<br />
The antenna element is supposed to be supported by three 40cm long PVC tubes and should hold the almost circular shape well thanks to the Aircoms' solid core conductor.<br />
<br />
The missing piece is the driven element. That is a small loop (1/5 of the main loop's diameter) I created out of <a href="http://www.ges.cz/cz/rg-58c-u-GES06700696.html">RG-58 coax cable</a> by connecting the end of center conductor to the outer braid half a meter away and making sure the braids do not touch at that point. I left about 10m of the cable going away from the connection point and added BNC connector to the end. That makes my feedline.<br />
<br />
Now with this done I was almost ready to transmit. I packed everything for the weekend except one small thing... <a href="http://www.ges.cz/cz/deleny-feritovy-filtr-fec-13-0-GES05500000.html">Ferrite core</a> to use as a base for balun. Five loops of my feedline through that core make the common mode impedance about 1500 ohm @ 10Mhz.<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh2ZUMheKBGLHBbJvA8XHBFcN1rZXNfcYpTcipQursRr6HvMRTU7ZqZ5e-bmkUYxsdDRZ1sVWE01-EHIGAc5UmMBpaBGdZzzUOjYFx5RKJe4BQL2d9iwcHkrmobsGq-42ikJ1a94ttS4EI7/s1600/mapa-destna.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh2ZUMheKBGLHBbJvA8XHBFcN1rZXNfcYpTcipQursRr6HvMRTU7ZqZ5e-bmkUYxsdDRZ1sVWE01-EHIGAc5UmMBpaBGdZzzUOjYFx5RKJe4BQL2d9iwcHkrmobsGq-42ikJ1a94ttS4EI7/s1600/mapa-destna.png" height="300" width="400" /></a></div>
<br />
<br />
Just before we started our trip to <a href="https://www.google.com/maps?q=velk%C3%A1+de%C5%A1tn%C3%A1&hl=en&ie=UTF8&sll=50.25183,16.423444&sspn=0.011429,0.01929&t=h&hnear=Velk%C3%A1+De%C5%A1tn%C3%A1&z=14">Velká Deštná</a> (<a href="http://www.sotawatch.org/summits.php?summit=OK/KR-008">OK/KR-008</a>, 1115m ASL) I forgot to pack the PVC tubes that were supposed to hold the shape of my loop. Oops..<br />
<br />
Fortunately, we found a nice straight dead tree branch to use as support and my son provided me with a <a href="http://www.babyrenka.cz/hracky-/kousatka-70000060/canpol-kousatko-elasticke-klice.html">fastener circle from his toy</a>. After this hack I connected my VNA to the feedline, watched the graphs on my cell phone using <a href="https://play.google.com/store/apps/details?id=ro.yo3ggx.btvna">BlueVNA</a> app and played with the capacitor. Tuning by turning an axle with fingers is no fun, but I managed to get the center frequency to about 14,250Mhz.<br />
<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiGSrap3yiLGZUYuXTSo8rcvzlzvzodexTrvr99cOLHKVSeo1N1xHY6hoSPRU6VVMGyu_Bl_PRKuIWeeIlq434vOcbXJFRCOf9w4yqHiaS40q2NbUsdi1Nd3cU2c62BKhnWLpyaHBwic7UD/s1600/IMG_4375m.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiGSrap3yiLGZUYuXTSo8rcvzlzvzodexTrvr99cOLHKVSeo1N1xHY6hoSPRU6VVMGyu_Bl_PRKuIWeeIlq434vOcbXJFRCOf9w4yqHiaS40q2NbUsdi1Nd3cU2c62BKhnWLpyaHBwic7UD/s1600/IMG_4375m.JPG" height="400" width="400" /></a></div>
<br />
<br />
I then connected the radio and listened for a while... well I was not happy to hear so much traffic and noise. Apparently there was a contest going on. Not much chance for me to call CQ with only 10W and SSB mode.<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj9gcyP1lzxAVjov5esytOeNhxhTRhSCg-VaS8h0rfcfBYrxsWBG3w0iy2K-pWLw2nTBW04RuHItKiQmmA7go1GEDFn_D7e_Ct0wMQQt7LOf9fZ87YnIG-TIkltqMq9Mf90ZzjaeghG6pRl/s1600/IMG_4373a.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj9gcyP1lzxAVjov5esytOeNhxhTRhSCg-VaS8h0rfcfBYrxsWBG3w0iy2K-pWLw2nTBW04RuHItKiQmmA7go1GEDFn_D7e_Ct0wMQQt7LOf9fZ87YnIG-TIkltqMq9Mf90ZzjaeghG6pRl/s1600/IMG_4373a.JPG" height="277" width="400" /></a></div>
<div class="separator" style="clear: both; text-align: center;">
<br /></div>
My first attempt on contact in that situation was therefore a sked with <a href="http://qrz.com/db/OK2JRQ">OK2JRQ</a>. I could barely hear his signal (QTH Brno, CZ, 100W), but since I operated with much lower power, he could not hear mine...<br />
<br />
Luckily I heard a CQ from a british special event station <a href="http://qrz.com/db/GX3EFX">GX3EFX</a> operated by Mike. After several attempts to get my callsign right he gave me a report of 44 due to a lot of noise coming at him from Europe. So my thanks to Britain.<br />
<br />
Then it started raining so it was time to pack the equipment and resume the trek. I never managed to do the required four contacts for SOTA activation, maybe next time.<br />
<br />
Overall it was an interesting attempt and I will be trying the antenna again for sure.MarSikhttp://www.blogger.com/profile/04703143981787504455noreply@blogger.com0Velká Deštná, 517 91 Deštné v Orlických horách, Czech Republic50.3022222 16.39777779999997224.780187700000003 -24.910816200000028 75.8242567 57.706371799999971tag:blogger.com,1999:blog-3943056659236945800.post-47063030792827871562014-03-26T15:15:00.001-07:002014-03-27T00:07:45.280-07:00Remote symmetric matchbox - part 4I finally completed the matchbox and did some preliminary testing with my network analyzer.<br />
<br />
The remote part was inserted into <a href="http://www.ges.cz/cz/kp-45-d-GES07200140.html">a waterproof box</a> and all external connections were waterproofed by using pigtails that go through water-tight cable sleeves.<br />
<br />
The external connections are:<br />
<ul>
<li>2x connection for symmetric antenna (<a href="http://www.andersonpower.com/products/singlepole-connectors.html">black connectors</a> on red wire)</li>
<li>asymetric RF input (pigtail with N female)</li>
<li>power (red and black wire with connectors)</li>
<li>control (UTP cable with RJ45 connectors, waterproofed by candle wax)</li>
</ul>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj4nLrljztbq4WItk7HKbH0MGmlt3Lck1DjozyQZbe6xB5XjgOTjfC6gvODFukHZmFLs63k35Bu2TDT24E74pu3V5a9Etvg3y-YSE9pTiEuUrAhy96Qyu1l_F2BpkVLPnOFE6QkJT4fJiuy/s1600/M3249433.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj4nLrljztbq4WItk7HKbH0MGmlt3Lck1DjozyQZbe6xB5XjgOTjfC6gvODFukHZmFLs63k35Bu2TDT24E74pu3V5a9Etvg3y-YSE9pTiEuUrAhy96Qyu1l_F2BpkVLPnOFE6QkJT4fJiuy/s1600/M3249433.jpg" height="480" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Almost completed matchbox in waterproof box.<br />
The only piece missing is the waterproofed RJ45 pigtail.</td></tr>
</tbody></table>
There are two things I would like point out before I continue:<br />
<br />
One component that was not described before is the input balun. To suppress the common mode current effectively the balun has to be on the low impedance side and that is the RF input. Look at the middle bottom of the coil board and you will see two coil wires entering a black cylinder with white rims. That is a set of five <a href="http://toroids.info/FT50-43.php">T50-43</a> toroid cores with 3 bifilar turns. The design impedance was about 500 ohms at 3.5Mhz.<br />
<br />
Another change I had to do was to solder a second inverter (<a href="https://www.fairchildsemi.com/ds/74/74ACT04.pdf">74ACT04</a>) on top of all the inverters I had on the relay driver board to boost the current capability. Driving two relays (coil switching) in parallel needed more juice (34mA) than a single output was able to provide.<br />
<br />
Now back to the testing…<br />
<br />
After I assembled the whole box I connected it to my <a href="http://miniradiosolutions.com/">miniVNA</a> and used 1000 ohm power (5W) resistor as a dummy load. I then checked that I am able to tune it to look like 50 ohm load.<br />
<br />
I was able to do it, but I quickly realized that I have made a mistake in the capacitor bank's relay wiring and the value I am sending over the control line has to be inverted (oops..). The coil switching is not affected by this as I fixed the polarity during <a href="http://ham.marsik.org/2014/03/remote-symmetric-matchbox-3.html">PCB layout</a> phase.<br />
<br />
So currently the control signal contains the following bytes:<br />
<ol>
<li>byte ignored</li>
<li>coil inductance; 0uH = 0x00, max uH = 0xff</li>
<li>capacitor capacitance; 0pF = 0xff, max pF = 0x00</li>
</ol>
<div>
I again used <a href="http://dangerousprototypes.com/docs/Bus_Pirate">Bus Pirate</a> for sending the SPI as I do not have the control box ready yet. All bytes were sent using 30kHz SPI with most significant bit first.</div>
<div>
<br /></div>
<div>
The command that matched 50 ohm output of the VNA to the power resistor was</div>
<blockquote class="tr_bq">
SPI>[0x00 0x1e 0xe9]</blockquote>
and the resulting values were close enough to the values predicted by <a href="http://www.ae6ty.com/Smith_Charts.html">SimSmith</a> (about 100pF and 4.9uH). Check the two following images to compare:<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh_iBRKl2TAoH3MZB07IyX_FOIjyOG4nmrxyZ0S8Fx4_xAzrWzJ4_qcVEI6PcHuvVQ_BGmPkfkNAPqEMwTu56u4ktqkZeKHUnlfv0q7VG7brFhupmrLNFAjUe0rIHvIxdUc4zqd2AOOF-my/s1600/smith-simsmith.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh_iBRKl2TAoH3MZB07IyX_FOIjyOG4nmrxyZ0S8Fx4_xAzrWzJ4_qcVEI6PcHuvVQ_BGmPkfkNAPqEMwTu56u4ktqkZeKHUnlfv0q7VG7brFhupmrLNFAjUe0rIHvIxdUc4zqd2AOOF-my/s1600/smith-simsmith.png" height="624" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="font-size: 13px;">Predicted impedance tuning in SimSmith</td></tr>
</tbody></table>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg8Fq5KhH3F8njmsvuZYwf_L8Go8GBt37iA5cufEUnLXwriSz_T5kkej9BIXQ7uiVDywdn3GGMX7RZYIZVvC8KDYXXMPhMEszNoTKX1Qv9FATMHUFPTzenr12_pQe0ATGjx4oqMxtHa0ywQ/s1600/tuned_ot.gif" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg8Fq5KhH3F8njmsvuZYwf_L8Go8GBt37iA5cufEUnLXwriSz_T5kkej9BIXQ7uiVDywdn3GGMX7RZYIZVvC8KDYXXMPhMEszNoTKX1Qv9FATMHUFPTzenr12_pQe0ATGjx4oqMxtHa0ywQ/s1600/tuned_ot.gif" height="574" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Measured impedance during step-by-step tuning</td></tr>
</tbody></table>
You might notice some small back-jumps in the tuning sequence. Those happen at places where multiple bits change (for example 0x0111 to 0x1000) and mean that the <span title="Most significant bit">MSb</span> coil does not have the full inductance of the three lower bit coils combined. Also the trajectory does not exactly follow the proper Smith chart lines which means there are some parasitic properties associated with the tuning elements.<br />
<br />
<div>
In case you wonder what software I use to talk to the Bus Pirate's serial interface then the answer is <a href="http://freeware.the-meiers.org/">Cool Term</a> when I am on Mac and <a href="http://en.wikipedia.org/wiki/Minicom">minicom</a> when I am using linux (Fedora in my case).</div>
<div>
<br /></div>
<div>
I hope I will get to connecting this matchbox to the antenna soon so I can evaluate the real world usability.</div>
<div>
<br /></div>
<div>
<br /></div>
<div>
<br /></div>
<div>
<br /></div>
MarSikhttp://www.blogger.com/profile/04703143981787504455noreply@blogger.com0tag:blogger.com,1999:blog-3943056659236945800.post-67524198841118012682014-03-17T01:40:00.000-07:002014-03-17T01:40:36.270-07:00Remote symmetric matchbox - part 3<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><div style="text-align: left;">
The last batch of PCBs finally arrived. So.. here I present you with the coil switching board for the symmetric matchbox.</div>
<div style="text-align: left;">
<br /></div>
<div style="text-align: left;">
As you can see the board is symmetric, but can be cut in half if that is needed. I have couple of</div>
<div style="text-align: left;">
extra and might use them for some other similar project that won't need both sections. </div>
<br />
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiV9ajlYUecJxAJXZpMUWms6HK5QDX4lWDx41BHl_V0yJVN1s9dGxW4qfbMC4hjmJ6fICZNrhueUZnWo3q9cH9I27iYxEDF955AsE5rC95fWR7kiLuHDRXf5J8dOzvMZsc-OwHL78bYgZ7H/s1600/Scan-140316-0001.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiV9ajlYUecJxAJXZpMUWms6HK5QDX4lWDx41BHl_V0yJVN1s9dGxW4qfbMC4hjmJ6fICZNrhueUZnWo3q9cH9I27iYxEDF955AsE5rC95fWR7kiLuHDRXf5J8dOzvMZsc-OwHL78bYgZ7H/s1600/Scan-140316-0001.jpg" height="368" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">PCB for coil switching board</td></tr>
</tbody></table>
The design inductance was 0 to 16uH per section in 256 steps. So I wound the coils on the Txx-6 cores that are good for HF signals (10-40Mhz). I used 0.6mm diameter enameled copper wire to make sure the biggest coil fits the core (42 turns).<br />
<br />
Check the winding table below:<br />
<table border="0" cellspacing="10" cols="5">
<thead>
<tr>
<th align="LEFT" height="18">L [uH]</th>
<th align="LEFT">core</th>
<th align="LEFT">Al / 100t</th>
<th align="LEFT">turns</th>
<th align="LEFT">Lr [uH]</th>
</tr>
</thead>
<tbody>
<tr>
<td align="RIGHT" height="17" sdnum="1029;" sdval="0,06">0,06</td>
<td align="LEFT">T50-6</td>
<td align="RIGHT" sdnum="1029;" sdval="40">40</td>
<td align="RIGHT" sdnum="1029;" sdval="4">4</td>
<td align="RIGHT" sdnum="1029;0;0,000" sdval="0,064">0,064</td>
</tr>
<tr>
<td align="RIGHT" height="17" sdnum="1029;" sdval="0,125">0,125</td>
<td align="LEFT">T50-6</td>
<td align="RIGHT" sdnum="1029;" sdval="40">40</td>
<td align="RIGHT" sdnum="1029;" sdval="6">6</td>
<td align="RIGHT" sdnum="1029;0;0,000" sdval="0,144">0,144</td>
</tr>
<tr>
<td align="RIGHT" height="17" sdnum="1029;" sdval="0,25">0,25</td>
<td align="LEFT">T50-6</td>
<td align="RIGHT" sdnum="1029;" sdval="40">40</td>
<td align="RIGHT" sdnum="1029;" sdval="8">8</td>
<td align="RIGHT" sdnum="1029;0;0,000" sdval="0,256">0,256</td>
</tr>
<tr>
<td align="RIGHT" height="17" sdnum="1029;" sdval="0,5">0,5</td>
<td align="LEFT">T50-6</td>
<td align="RIGHT" sdnum="1029;" sdval="40">40</td>
<td align="RIGHT" sdnum="1029;" sdval="11">11</td>
<td align="RIGHT" sdnum="1029;0;0,000" sdval="0,484">0,484</td>
</tr>
<tr>
<td align="RIGHT" height="17" sdnum="1029;" sdval="1">1</td>
<td align="LEFT">T50-6</td>
<td align="RIGHT" sdnum="1029;" sdval="40">40</td>
<td align="RIGHT" sdnum="1029;" sdval="16">16</td>
<td align="RIGHT" sdnum="1029;0;0,000" sdval="1,024">1,024</td>
</tr>
<tr>
<td align="RIGHT" height="17" sdnum="1029;" sdval="2">2</td>
<td align="LEFT">T68-6</td>
<td align="RIGHT" sdnum="1029;" sdval="47">47</td>
<td align="RIGHT" sdnum="1029;" sdval="21">21</td>
<td align="RIGHT" sdnum="1029;0;0,000" sdval="2,0727">2,073</td>
</tr>
<tr>
<td align="RIGHT" height="17" sdnum="1029;" sdval="4">4</td>
<td align="LEFT">T68-6</td>
<td align="RIGHT" sdnum="1029;" sdval="47">47</td>
<td align="RIGHT" sdnum="1029;" sdval="29">29</td>
<td align="RIGHT" sdnum="1029;0;0,000" sdval="3,9527">3,953</td>
</tr>
<tr>
<td align="RIGHT" height="17" sdnum="1029;" sdval="8">8</td>
<td align="LEFT">T80-6</td>
<td align="RIGHT" sdnum="1029;" sdval="45">45</td>
<td align="RIGHT" sdnum="1029;" sdval="42">42</td>
<td align="RIGHT" sdnum="1029;0;0,000" sdval="7,938">7,938</td>
</tr>
</tbody></table>
<br />
<div class="separator" style="clear: both; text-align: center;">
</div>
<div class="separator" style="clear: both; text-align: center;">
</div>
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhWrjBNYr4G5ykIpn9l0NRejd-9_qDHZiBw6kkCMiTNu0G6_S_SyyRC8ZDl2uEplFznMqf52mHwRIDuIxO4jOrq29Eek0csjhNCoQkcnH0hckcWbU0pEfIZZN89nLbBLHfhm1YqTJr78V-9/s1600/20140317_092227.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhWrjBNYr4G5ykIpn9l0NRejd-9_qDHZiBw6kkCMiTNu0G6_S_SyyRC8ZDl2uEplFznMqf52mHwRIDuIxO4jOrq29Eek0csjhNCoQkcnH0hckcWbU0pEfIZZN89nLbBLHfhm1YqTJr78V-9/s1600/20140317_092227.jpg" height="480" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Populated coil switching board</td></tr>
</tbody></table>
<br />MarSikhttp://www.blogger.com/profile/04703143981787504455noreply@blogger.com0tag:blogger.com,1999:blog-3943056659236945800.post-89348669382569831712014-02-02T06:34:00.001-08:002014-02-02T06:34:57.253-08:00Remote symmetric matchbox - part 2I finally got to soldering the <a href="http://ham.marsik.org/2014/01/remote-symmetric-matchbox.html">PCBs for my tuner</a>. Here is the picture of the result hooked up to my <a href="http://dangerousprototypes.com/docs/Bus_Pirate">Bus Pirate</a> for testing:<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhhCV_sfO8GVBSNJfRupc1FkymS27TuHKbVG29NBBQNhl-VRxw8_rcw-tYbLO6eM9bdLzWaF-KNXAQnwzVdwZiO74bIpN1Ovu7E7deGiT7-tGzJ-5Uhiae02i-3jH41FVYRdB6UWG_-k89C/s1600/P2029105.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhhCV_sfO8GVBSNJfRupc1FkymS27TuHKbVG29NBBQNhl-VRxw8_rcw-tYbLO6eM9bdLzWaF-KNXAQnwzVdwZiO74bIpN1Ovu7E7deGiT7-tGzJ-5Uhiae02i-3jH41FVYRdB6UWG_-k89C/s1600/P2029105.jpg" height="480" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Bus Pirate hooked up to control boards and capacitor bank board.<br />
From the left side: Bus Pirate; SPI to UTP convertor; Capacitor board; UTP decoder and 3x8 relay driver board</td></tr>
</tbody></table>
The capacitor board can switch in capacitances between (design values) 3.7pF and 947pF.<br />
<br />
It consists of 8 binary switched banks where each bank has three sections in series (to increase breakdown voltage) with two caps in parallel in each (to improve current carrying capability). All capacitors are zero temperature coefficient (NP0) ceramics rated for 500V.<br />
<br />
<table cellpadding="1" cellspacing="7">
<thead>
<tr><th>bank</th><th>total</th><th>section 1</th><th>section 2</th><th>section 3</th></tr>
</thead>
<tbody>
<tr><td>1.</td><td>3.7pF</td><td>2x 5.6pF</td><td>2x 5.6pF</td><td>2x 5.6pF
</td></tr>
<tr><td>2.</td><td>7.5pF</td><td>2x 10pF</td><td>2x 12pF</td><td>2x 12pF
</td></tr>
<tr><td>3.</td><td>14.7pF</td><td>2x 22pF</td><td>2x 22pF</td><td>2x 22pF
</td></tr>
<tr><td>4.</td><td>30.3pF</td><td>2x 39pF</td><td>2x 39pF</td><td>2x 68pF
</td></tr>
<tr><td>5.</td><td>57.6pF</td><td>2x 68pF</td><td>2x 100pF</td><td>2x 100pF
</td></tr>
<tr><td>6.</td><td>120pF</td><td>2x 180pF</td><td>2x 180pF</td><td>2x 180pF
</td></tr>
<tr><td>7.</td><td>231.9pF</td><td>2x 330pF</td><td>2x 330pF</td><td>2x 390pF
</td></tr>
<tr><td>8.</td><td>480.7pF</td><td>2x 680pF</td><td>2x 680pF</td><td>2x 820pF
</td></tr>
</tbody>
</table>
<br />
<div>
Once I (create and) connect the toroid board and input balun, the tuner will be ready for field testing.</div>
MarSikhttp://www.blogger.com/profile/04703143981787504455noreply@blogger.com0tag:blogger.com,1999:blog-3943056659236945800.post-74406550654050554852014-01-07T13:05:00.002-08:002014-01-07T13:55:19.243-08:00First QSLs received through buroI have just received my first two way QSL cards through buro. It took only half a year :)<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgLD81-KunYs0Bmtagj1MMKmalsPo9hiJJhx90U0IyXCUg2c7UApNeD79bnFOnH8mMguhqw8jzVB8nm4mCZdbEsjngNskMBzW_F4-AuBmECfnmea3_dG-8BmfVAgZCbFSVf2qBUpQq4-vGA/s1600/Scan-140107-0005.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgLD81-KunYs0Bmtagj1MMKmalsPo9hiJJhx90U0IyXCUg2c7UApNeD79bnFOnH8mMguhqw8jzVB8nm4mCZdbEsjngNskMBzW_F4-AuBmECfnmea3_dG-8BmfVAgZCbFSVf2qBUpQq4-vGA/s1600/Scan-140107-0005.jpg" height="320" width="207" /></a></div>
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjdyF58eaZxYu8MC356xGGzJqm0LW7kK0jVqx1kqbfgVYP-8ouAZiWMC2I7BS3nHHBNIt9CLQsdNciQy4aMElOjynZNJQlcgAwtJvZ02UV5qnKxRnMcj7qe2-KdZRXgsWk7kR6O4WACQ75m/s1600/Scan-140107-0006.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjdyF58eaZxYu8MC356xGGzJqm0LW7kK0jVqx1kqbfgVYP-8ouAZiWMC2I7BS3nHHBNIt9CLQsdNciQy4aMElOjynZNJQlcgAwtJvZ02UV5qnKxRnMcj7qe2-KdZRXgsWk7kR6O4WACQ75m/s1600/Scan-140107-0006.jpg" height="207" width="320" /></a></div>
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgupBDek5RHPMu0JcHLHVTeixNix0AsgjqTOxibNLhkJEUlxL3PxMFgKl0uD1wGYo38EsM2QY0kxdmzmtyWcrYyAPeDn_AOKhKSeuRsQHjm6Bl_4xlv-ILYKLmloqqlDi2UlSjvvw8ZoqsI/s1600/Scan-140107-0007.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgupBDek5RHPMu0JcHLHVTeixNix0AsgjqTOxibNLhkJEUlxL3PxMFgKl0uD1wGYo38EsM2QY0kxdmzmtyWcrYyAPeDn_AOKhKSeuRsQHjm6Bl_4xlv-ILYKLmloqqlDi2UlSjvvw8ZoqsI/s1600/Scan-140107-0007.jpg" height="207" width="320" /></a></div>
<br />
<br />
Couple of months ago I also asked for one QSL to be delivered direct as it was my first contact with an Asia station. So here it is.<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh1GkhpYsT6c3FagPbD-q7Ynd9ehTbqO3Cww3S1YrB6N4mGDCrLDW9TbpxVUUr8FbPg-1M3NLPzVb29odBmO3kbO5TneXEM6kL2WZvUuV-Sm3cGYxO_BtsKeBVfNqmxlqoEODn2pn8rvQge/s1600/Scan-140107-0008.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh1GkhpYsT6c3FagPbD-q7Ynd9ehTbqO3Cww3S1YrB6N4mGDCrLDW9TbpxVUUr8FbPg-1M3NLPzVb29odBmO3kbO5TneXEM6kL2WZvUuV-Sm3cGYxO_BtsKeBVfNqmxlqoEODn2pn8rvQge/s1600/Scan-140107-0008.jpg" height="214" width="320" /></a></div>
<br />MarSikhttp://www.blogger.com/profile/04703143981787504455noreply@blogger.com0tag:blogger.com,1999:blog-3943056659236945800.post-44075275251324396152014-01-07T12:36:00.002-08:002014-01-07T13:55:02.844-08:00Remote symmetric matchboxHere is my second attempt to create a symmetric matchbox for my QRP purposes. I quickly realized that it is quite annoying to run to the antenna to retune after a frequency change. So I decided to create a remote matchbox based on my <a href="http://ham.marsik.org/2013/08/multiband-dipole-ladder-line-and.html">previous manual one</a>.<br />
<div>
<br />
There are <a href="http://www.hamware.de/hardware/tuner615B/at615B-e.htm">some</a> <a href="http://www.palstar.com/en/bt1500a/">commercial</a> balanced matchboxes. The single remote one (HamWare AT-615B) is VERY expensive and uses a lot of control wires.<br />
<br />
When I saw that I decided on three main design goals for my prototype:<br />
<br />
<ul>
<li>no micro controller on the antenna side</li>
<li>immunity to interference</li>
<li>simple wiring</li>
</ul>
<br />
So I started thinking about the control interface and realized that if UTP 5e is good for 100 meter long lines up to gigabit speeds it must surely be good for low frequency as well. UTP gives me four differential pairs to use. SPI then needs four wires and can control a shift register directly. This combined will allow me to reuse my stash of UTP 5e cable and connectors and when I do not have any more UTP is quite cheap anyway.</div>
<div>
<br /></div>
<div>
Here are the first steps I took.. schematics and PCBs. I could have used ground plane construction, but I was a bit worried about the capacitance it would create.</div>
<div>
<br /></div>
<div>
I have already mentioned that I am using SPI as the control protocol and here is how I envision it to work:</div>
<div>
<ul>
<li>A micro uses SPI to send 24 bits over to the tuner. Each bit controls one bipolar relay, together they control three sets of eight relays each.</li>
<li>Each SPI signal is converted to a differential pair (5V/0V levels) to prevent interference and transfered in that form to the tuner side controller. Each signal is using one twisted pair in the UTP cable.</li>
<li>At the tuner side the pair is decoded to SPI signals again and those are connected to three 74HC595 latching shift registers (24 bits).</li>
<li>The shift registers hold the control value and pass the bit values to 74ACT04 invertors that drive the bipolar relays (FTR-B4).</li>
<li>The ACT family can source or sink more than 20mA per leg. That is more than enough to switch the state of my relays.</li>
</ul>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><span style="background-color: white; color: white;"><br /><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgcNfSG6kiPRmdPloPSifaseEBfPSedzyANycCTCVJhrng6tH2t7OvwPBizszNy9pNNeisa3FAfqL23f39xnaW3tapjDGbP764WFiCMM7lEYoBkFuSA1sLWym2M5O59vmBLgbPRNFT65GrA/s1600/console-ctrl.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgcNfSG6kiPRmdPloPSifaseEBfPSedzyANycCTCVJhrng6tH2t7OvwPBizszNy9pNNeisa3FAfqL23f39xnaW3tapjDGbP764WFiCMM7lEYoBkFuSA1sLWym2M5O59vmBLgbPRNFT65GrA/s1600/console-ctrl.png" height="451" style="background-color: white;" width="640" /></a></span></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Transceiver side controller - SPI to UTP</td></tr>
</tbody></table>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgFy4QEWfa3BM4m_i_1YxkBFiXYDsD_TQSEXNs8eFyYWbbChbXqnLLXR32QEaWUuvHXM7Y0qA04tz4ka7gpwhElzEw6yTBYJz9TctBYTVz9ifvsQKBQABYu6FzXGmcQWMILnduzKAyT2Mpi/s1600/remote-ctrl.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgFy4QEWfa3BM4m_i_1YxkBFiXYDsD_TQSEXNs8eFyYWbbChbXqnLLXR32QEaWUuvHXM7Y0qA04tz4ka7gpwhElzEw6yTBYJz9TctBYTVz9ifvsQKBQABYu6FzXGmcQWMILnduzKAyT2Mpi/s1600/remote-ctrl.png" height="451" style="background-color: white;" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Tuner side controller - UTP to relay controller lines</td></tr>
</tbody></table>
The controller boards use <a href="http://www.ti.com/lit/ds/slls104i/slls104i.pdf">AM26C32CD</a> receivers and <a href="http://www.st.com/web/en/resource/technical/document/datasheet/CD00002005.pdf">ST26C31B</a> drivers. I know I am wasting one perfectly good receiver/driver, but I have quite lot of those in my stash :)<br />
<br />
The<a href="http://en.wikipedia.org/wiki/Category_5_cable#Characteristics"> characteristic impedance of UTP twisted pair</a> is 100 ohms, the same as the output impedance of the ST26C31 driver (see Table 6 in the datasheet). For that reason there are 100 ohm terminating resistors just before the receivers.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgLDTDzUk-N-mlr1zYMs2lOCKbKUewsCOT4bqXi65-uaJLwFKbPfPsAjtFLyVMwseYeEIDiGRsR6tb3gotp7ftlNm_bOmCCz_XXVpBUEYG1tWkoFcQFSOrCCu7vCLJlTkksO4dynhvHkr4L/s1600/switching-L.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgLDTDzUk-N-mlr1zYMs2lOCKbKUewsCOT4bqXi65-uaJLwFKbPfPsAjtFLyVMwseYeEIDiGRsR6tb3gotp7ftlNm_bOmCCz_XXVpBUEYG1tWkoFcQFSOrCCu7vCLJlTkksO4dynhvHkr4L/s1600/switching-L.png" height="451" style="background-color: white;" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Coil switching board</td></tr>
</tbody></table>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiRrzYSOv5TuDvCC534mDC7yXqlAXvDjJLfXugGZZv2oP9fiqIctSmPZ5KMT0WHG9cBzTp7vhRYsHzOL7mkSw1_yCrcdHZWhrULbNebTkZ72SkFurw7aHSRrzffcknOqYpQ8EEWKGIlY4w4/s1600/switching-C.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiRrzYSOv5TuDvCC534mDC7yXqlAXvDjJLfXugGZZv2oP9fiqIctSmPZ5KMT0WHG9cBzTp7vhRYsHzOL7mkSw1_yCrcdHZWhrULbNebTkZ72SkFurw7aHSRrzffcknOqYpQ8EEWKGIlY4w4/s1600/switching-C.png" height="451" style="background-color: white;" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Capacitor bank board</td></tr>
</tbody></table>
Coil and capacitor switching circuits are not special at all:<br />
<br />
<ul>
<li>Coils are connected in parallel and single coils can be bypassed by the respective relay.</li>
<li>Capacitors are organized into banks where each bank can have 16 capacitors - four parallel capacitors four times in series to make the bank withstand higher voltages (I have assortment of 500V NP0 capacitors).</li>
<li>All relays are bipolar (latching) <a href="http://www.fujitsu.com/downloads/MICRO/fcai/relays/ftr-b4.pdf">Fujitsu FTR-B4 4.5V</a> with 17mA latching current. I am only using QRP power so the current carrying capability (1A per section and I wire both sections in parallel). I am using the same trick to drive them as in my manual matchbox from the previous article.</li>
</ul>
<br />
I am planning to use balanced-Pi configuration and haven't decided on the capacitor values yet so I planned for the worst case. I won't probably be populating most of the capacitors. All of them will be the NP0 kind though (zero temperature coefficient).<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh_lF7VnVhUQUY5S4q_DQXcTxmuYrfB2VPcfI93At9lsNtM6zDBngryCGswGKGwy_7NznIvNo0JpCKCsADc6XQ7HpCZOTBUCLOjZBf6nuCUjrQGEIWLGyuaO63fYbGNkuQdOfYOvAWqXlxa/s1600/Scan-140107-0002.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh_lF7VnVhUQUY5S4q_DQXcTxmuYrfB2VPcfI93At9lsNtM6zDBngryCGswGKGwy_7NznIvNo0JpCKCsADc6XQ7HpCZOTBUCLOjZBf6nuCUjrQGEIWLGyuaO63fYbGNkuQdOfYOvAWqXlxa/s1600/Scan-140107-0002.jpg" height="330" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Panel with controller boards (tuner and trx sides) + one unrelated micro-controller board</td></tr>
</tbody></table>
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhOnrGG3WeNSzO-oanAm1wDhzevRltNjgCz0lWNkFXPlBgRmwI9dBD3UJDFCZUSPyp6QgkEiFawRSgFJdJDF0twx_j5yc5twB0q_eJekU2TSIkEmrMChWnR90ljr5xUT8JryFZyRosMztdV/s1600/Scan-140107-0003.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhOnrGG3WeNSzO-oanAm1wDhzevRltNjgCz0lWNkFXPlBgRmwI9dBD3UJDFCZUSPyp6QgkEiFawRSgFJdJDF0twx_j5yc5twB0q_eJekU2TSIkEmrMChWnR90ljr5xUT8JryFZyRosMztdV/s1600/Scan-140107-0003.jpg" height="330" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Two capacitor bank boards with relays</td></tr>
</tbody></table>
The boards were made by <a href="http://www.seeedstudio.com/service/index.php?r=site/pcbService">Seeedstudio</a> and it took about a month to get them. I was busy during that time so it was not really holding me back.. but I am glad I have them at home. You might have also noticed that there is no board for the coil part. That is because I am planning on reusing the board I already have in the manual matchbox.<br />
<br />
That I all I can describe today as I haven't started soldering yet. Once I have a prototype ready, I will post the results.</div>
MarSikhttp://www.blogger.com/profile/04703143981787504455noreply@blogger.com1tag:blogger.com,1999:blog-3943056659236945800.post-70502791015324435822013-08-27T04:35:00.000-07:002014-01-07T13:54:41.408-08:00Multiband dipole, ladder line and homebrew manual symmetric matchboxI recently found out that my dipole was a bit shorter than it should be. Since I use 75 ohm HDTV coax (<a href="http://www.nordixkabely.cz/download/datasheet/Nordix_CM_407cu.pdf">Nordix CM407 Cu PE</a>) as my feedline, I was losing power in the impedance mismatch. I also started to be a bit annoyed by it being single band only. So I started looking for a possible solution.<br />
<br />
The only reasonable change I could do regarding antenna was to use a bit longer wire (about 44 feet), ladder line and a matchbox to match it to the 75 ohm feedline. This is the basic concept of non-resonant multiband dipole as described in ARRL Handbook and Antenna book.<br />
<br />
I built the feedline out of 0.5mm^2 insulated stranded wire (because I have plenty..) and cut 6mm diameter hard irrigation tubing (black, 15m for 99Kč - 4€ in a local hobby store) to pieces to make the separators. I then cut slots to the separators, inserted wire and secured using black plastic cable ties. I tried many different ways of making the ladder line, but this way was the fastest and cheapest.<br />
<br />
Then I started looking at the available ATUs and quickly figured out that the prices are very high. I won't describe the details as DJ0IP already dedicated many pages to this topic at his <a href="http://www.dj0ip.de/antenna-matchboxes/symmetrical-matchboxes/">website</a>.<br />
<br />
Since I am only interested in low power (10W max) it was quite easy to come up with home-brew solution. It is a switchable L network with 16 coils (2 times 8 to make it symmetric) and a variable capacitor <a href="http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=151092189767">I got at ebay</a> wired as split stator (the two sections in series). I also added one additional fixed 200pF/1000V (2x4x100pF/500V NP0) capacitor that can be switched in and out of the circuit.<br />
<br />
There is also an 1:1 current balun (7 bifilar turns on FT50-43) at the input side of the tuner.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhhhR0b54BEmCcc9g54Idl5kysJahMkwzNwJc1SuMWpBL8Vt5V_kdQt7MfHUfsjwF-8Yvq6mJTo2tm7kQVwJ9GVnUqmwjM6ZF8mFcMX8cxDFmIdYvxvLZZAoWCp6Wx6SftybULm1wiqByG3/s1600/20130821_091702.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhhhR0b54BEmCcc9g54Idl5kysJahMkwzNwJc1SuMWpBL8Vt5V_kdQt7MfHUfsjwF-8Yvq6mJTo2tm7kQVwJ9GVnUqmwjM6ZF8mFcMX8cxDFmIdYvxvLZZAoWCp6Wx6SftybULm1wiqByG3/s320/20130821_091702.jpg" height="320" width="240" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Components before wiring. There is the 200pF/1000V capacitor at the top (the PCB)<br />
and the relay controller board in the middle.</td></tr>
</tbody></table>
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhO4v6Qg5E_rF8wpdL_8Nh_lW8L53G0_2O6TTEcpBLrwMG35-IO-KKiqJr_jmI61kGUYNJOUDmDzZYWuCJjXPnSWxZnvv8VggXV3FWVegaLcT0J50xFGVmORlXksF_gqbsRS-ef2a_TD9-v/s1600/20130821_091717.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhO4v6Qg5E_rF8wpdL_8Nh_lW8L53G0_2O6TTEcpBLrwMG35-IO-KKiqJr_jmI61kGUYNJOUDmDzZYWuCJjXPnSWxZnvv8VggXV3FWVegaLcT0J50xFGVmORlXksF_gqbsRS-ef2a_TD9-v/s320/20130821_091717.jpg" height="240" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Front panel (I added one more switch later).<br />
You can also see the current balun at the back side right from the BNC connector.</td></tr>
</tbody></table>
Coil switching is accomplished by <a href="http://www.fujitsu.com/downloads/MICRO/fcai/relays/ftr-b4.pdf">FTR-B4 4.5V locking relays </a>(or bipolar as we call them in CZ) that are directly controlled by front panel switches. I decided to do it this way to minimize wiring length and parasitic effects. The circuit is powered by single cell LiPol battery (3.7V nominal) that is used only when relays change state and so will stay charged for a long time.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjZvLAfy0LGHxnDlrh5js6xuHBUzE-X1dgUkkr26AldAbi1McCIVxkRKbpG0qYKoBELKBYZgPzWEzyGre2-IujR12FnFRZDH7N_k9lrzi8JmZ-jOzkIW65Uhkw_etDQXUiJMgS0mQ-PbFn9/s1600/20130821_091255.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjZvLAfy0LGHxnDlrh5js6xuHBUzE-X1dgUkkr26AldAbi1McCIVxkRKbpG0qYKoBELKBYZgPzWEzyGre2-IujR12FnFRZDH7N_k9lrzi8JmZ-jOzkIW65Uhkw_etDQXUiJMgS0mQ-PbFn9/s320/20130821_091255.jpg" height="240" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Coils, relays and the control cable on a copper clad board.</td></tr>
</tbody></table>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjMGiIFInnZzdRbugJauDfjK8rdIKMZUS6t2bclyzv13bLIIx-nOhJ979T3E1PwhXKZ9tVEjZKDSffTc-CRGmwKGnJaLbj4VpGTcHlgxWfabhB77pHgfFFfX4U8INmmdQlEleTjQ9o6WmUb/s1600/relay-ctrl.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjMGiIFInnZzdRbugJauDfjK8rdIKMZUS6t2bclyzv13bLIIx-nOhJ979T3E1PwhXKZ9tVEjZKDSffTc-CRGmwKGnJaLbj4VpGTcHlgxWfabhB77pHgfFFfX4U8INmmdQlEleTjQ9o6WmUb/s320/relay-ctrl.png" height="203" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Simulation circuit of the relay controller. R1 is the relay coil and V1 is the switch.</td></tr>
</tbody></table>
All the coils were wound on toroids from the <a href="http://www.ferroxcube.com/prod/assets/4c65.pdf">Ferroxcube 4c65</a> material. I used three different sizes of cores (9mm, 14mm and 23mm OD) and I wound the inductances so they are about 0.125uH, 0.25uH, 0.5uH, 1uH, 2uH, 4uH, 8uH and 16uH. Since there are two coils of the same inductance in symmetric series it gives me an inductance range of about 0.25uH to about 64uH.<br />
<div>
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhtAlnzo19yfqndUAzlS_b4w0fNkYCcu5cQ0t5HXHarrQAFqqXRa014dzHnFDc0kK7L3KeDZ1qimafNP0alenLZV1FnNCvfqzT3ZhqW5THSsrF_G5GUr7ElEETL0VD6WB_MlS31tMrT0f05/s1600/20130827_132236.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhtAlnzo19yfqndUAzlS_b4w0fNkYCcu5cQ0t5HXHarrQAFqqXRa014dzHnFDc0kK7L3KeDZ1qimafNP0alenLZV1FnNCvfqzT3ZhqW5THSsrF_G5GUr7ElEETL0VD6WB_MlS31tMrT0f05/s320/20130827_132236.jpg" height="240" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">The finished matchbox</td></tr>
</tbody></table>
<div>
The result was an "ugly" box that is able to match my antenna at least on 20m and higher. Those are the bands I wanted to use. I used my miniVNA with vna/J in Smith chart mode to find the settings for different frequencies. The settings for 20m and my dipole were 3.75uH and minimal possible capacitance connected to the antenna side. The fact that I tried to learn how a <a href="http://www.ieee.li/pdf/viewgraphs/smith_chart_tutorial.pdf">Smith chart works</a> helped me a lot when figuring out the values :).<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
</div>
</div>
MarSikhttp://www.blogger.com/profile/04703143981787504455noreply@blogger.com0tag:blogger.com,1999:blog-3943056659236945800.post-74463617496189456652012-12-23T14:28:00.000-08:002014-01-07T13:53:09.902-08:00Baofeng UV-3R in packet world using ArduinoTNCSince it is so cheap and works reasonably well for 2m/70cm band in FM mode, I wanted to test also it's capabilities as FM modulator for AFSK digi modes and APRS.<br />
<br />
First I needed a cable to connect to the radio. Fortunately that is relative easy and requires only four ring 3.5" jack and some standard components.<br />
<br />
The cable pinout is easy:<br />
<br />
<div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="color: red; margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgVSD6TamFP4P7HftHWEwOUKucVgE6kl_OC8QOppUEMZtzBzpgBOn24vfy1sc9hJ9d75XszNCwrMuLbmcsqKXqKPaAUr-0PEH-Yl4XzcXt0J0Qq14ZOZw4YWh6drwnr_J2fkEkEewreccXA/s1600/BaofengUV3R-TNCcable.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgVSD6TamFP4P7HftHWEwOUKucVgE6kl_OC8QOppUEMZtzBzpgBOn24vfy1sc9hJ9d75XszNCwrMuLbmcsqKXqKPaAUr-0PEH-Yl4XzcXt0J0Qq14ZOZw4YWh6drwnr_J2fkEkEewreccXA/s320/BaofengUV3R-TNCcable.png" height="230" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span class="Apple-style-span" style="color: black;">Baofeng UV-3R TNC cable</span></td></tr>
</tbody></table>
<div style="color: red;">
<span class="Apple-style-span" style="color: black;"><br /></span></div>
To get to the packet world a TNC is needed. I was experimenting with different software solutions (soundmodem, agwpe), but this test was done with Arduino based TNC (because I had one laying around and it has USB to serial chip on board).</div>
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhx936k1OqUmW9GXIBDyY67s87RX7nd_40tESjo4a1JA99LX1LeKODjuhdR_GBkTiuO1r-1Kg_8BcLfQHbgjde5rHp4crhmhWznY2f5VyNfglO91dihr9GkWRHLudz_azVknJqOg4nze3T0/s1600/MC238571.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhx936k1OqUmW9GXIBDyY67s87RX7nd_40tESjo4a1JA99LX1LeKODjuhdR_GBkTiuO1r-1Kg_8BcLfQHbgjde5rHp4crhmhWznY2f5VyNfglO91dihr9GkWRHLudz_azVknJqOg4nze3T0/s320/MC238571.jpg" height="240" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">ArduinoTNC shield and cable</td></tr>
</tbody></table>
<br />
<br />
The design is based on <a href="https://sites.google.com/site/ki4mcw/Home/arduino-tnc">KI4MCW's</a>, but the software was updated to work well with latest <a href="http://www.bertos.org/">BertOS</a> (2.7.0) and to support KISS escapes and command structure.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh9TdgvmZmony0na9rmBNcZKPrKV0jvLhrvO80YKdolY5YIjMz1qd0la_ingtucGFQaPqMDzhHI8bbb2MJywC54zzfXlQfc3JqdpkXC6zh5XUE9tWyNXgHMILUBY-84Ecgy-xcCpKzKhseX/s1600/ArduinoTNC.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh9TdgvmZmony0na9rmBNcZKPrKV0jvLhrvO80YKdolY5YIjMz1qd0la_ingtucGFQaPqMDzhHI8bbb2MJywC54zzfXlQfc3JqdpkXC6zh5XUE9tWyNXgHMILUBY-84Ecgy-xcCpKzKhseX/s640/ArduinoTNC.png" height="400" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Arduino TNC schematics (the filter cap on PTT line is missing here)</td><td class="tr-caption" style="text-align: center;"><br /></td></tr>
</tbody></table>
<br />
You can also download the <a href="https://dl.dropbox.com/u/13472947/ArduinoTNC.zip">complete source codes</a> (complete with configured BertOS).<br />
<br />
The TNC was connected to Xastir running on Mac OS X with the proper settings - Serial KISS TNC, 19200baud, /dev/cu.usbmodem24311 and "Transmit now" was triggered.<br />
<br />
The radio switched to TX mode and... stayed transmitting. Oops. RF noise induced enough energy on the unshielded Arduino to trigger the PTT optocoupler and keep it triggered.<br />
<br />
All that was needed to remedy this was to connect one SMD ceramic 100nF cap between PTT line and ground.<br />
<br />
With that done, I triggered Transmit now again and measured what happened:<br />
<ul>
<li>Blue line (CH1) measures the PTT line on the PCB (pin 11/PORTB3)</li>
<li>Red line is the audio output of the simple DAC, measured before the pot</li>
</ul>
With STE turned on in the menu, the radio showed about 230ms PTT to TX delay and 300ms TX tail as you can see on the attached pictures (watch the RF induced noise on the blue PTT line).<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgK9mU0rUkfWOLwlRR1f4IPyAqXwR6jwtUR_8Q_Xo0v1cse7THnDdYpw-x36AKYaTz_qVon3Dc1-4QOGprJY1GxGgBXFqgfIYg4nw7Ztx1HvP7sCPlnM_C7vVe6GXRU7UO_7mAnUXNp7lmq/s1600/ptt_begin0.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgK9mU0rUkfWOLwlRR1f4IPyAqXwR6jwtUR_8Q_Xo0v1cse7THnDdYpw-x36AKYaTz_qVon3Dc1-4QOGprJY1GxGgBXFqgfIYg4nw7Ztx1HvP7sCPlnM_C7vVe6GXRU7UO_7mAnUXNp7lmq/s400/ptt_begin0.png" height="292" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">TxDelay with STE on</td><td class="tr-caption" style="text-align: center;"></td></tr>
</tbody></table>
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjOxqELBq2n83rI19v3hb4_eWoOkcu3Bl386MTaKB22iCe0yqcwXofAUUdeGvX9hE1V_Jemvx2Jb4K3yEx8f9KmcG4lW0SstkICnC6sCzgNkowXGz3xXMSt882OxJTWrfXovjHrCA05-T9P/s1600/ptt_end0.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjOxqELBq2n83rI19v3hb4_eWoOkcu3Bl386MTaKB22iCe0yqcwXofAUUdeGvX9hE1V_Jemvx2Jb4K3yEx8f9KmcG4lW0SstkICnC6sCzgNkowXGz3xXMSt882OxJTWrfXovjHrCA05-T9P/s400/ptt_end0.png" height="292" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">TxTail with STE on</td></tr>
</tbody></table>
<br />
The TX tail was pretty long so I turned the STE (Tail tone elimination) function off and tried again:<br />
<div style="color: red;">
<b><br /></b></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEifNbHIw0FxGMEdWnXeW2A9mErir_vYeAA9EG3Dz0y8fmsDoUpGCcsItPkcKve3BMpzRt1BVsJFfdX2tW8QFJmhGVTdK_xq8AN82jpPNmsqOcdWG5kdIzCZV3VRQeD_Xc4hMOutTcbg0et_/s1600/STEoffTXTail.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEifNbHIw0FxGMEdWnXeW2A9mErir_vYeAA9EG3Dz0y8fmsDoUpGCcsItPkcKve3BMpzRt1BVsJFfdX2tW8QFJmhGVTdK_xq8AN82jpPNmsqOcdWG5kdIzCZV3VRQeD_Xc4hMOutTcbg0et_/s400/STEoffTXTail.png" height="292" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">TxTail with STE off</td></tr>
</tbody></table>
<br />
With full power, STE turned off and resistance between the pot wiper and ground measured as 572 ohm the transmission was finally properly received by our local IGATE (9.2 km). So the UV-3R is indeed usable as an APRS transmitter.<br />
<br />MarSikhttp://www.blogger.com/profile/04703143981787504455noreply@blogger.com0tag:blogger.com,1999:blog-3943056659236945800.post-8839910310975315372012-12-10T08:06:00.000-08:002014-01-07T13:55:46.182-08:00My first foreign QSL cardI have just received a QSL card from Japan. It is my first QSL card from abroad and also my first satellite reception ever. :)<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEho2NHxeAjGfBtsakqY1rfNDBKLyks2nMu_tAGMTQjWl-W3rNVsimrjeEd4k1U-hA17gjIGIX0KdUKk8rdn61RdohLtnAcePYo68n2tFjcmRCnoz58_1nw6K2ZWi00blT2LoFEWZhklLzo5/s1600/Scan-121210-0001.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEho2NHxeAjGfBtsakqY1rfNDBKLyks2nMu_tAGMTQjWl-W3rNVsimrjeEd4k1U-hA17gjIGIX0KdUKk8rdn61RdohLtnAcePYo68n2tFjcmRCnoz58_1nw6K2ZWi00blT2LoFEWZhklLzo5/s320/Scan-121210-0001.jpg" height="217" width="320" /></a></div>
<br />
Not bad considering I have used the first version of FUNCube dongle and a corner reflector antenna mounted in the middle of the wall of an apartment building.MarSikhttp://www.blogger.com/profile/04703143981787504455noreply@blogger.com1tag:blogger.com,1999:blog-3943056659236945800.post-60421858809310727022012-02-27T07:32:00.000-08:002012-02-27T07:32:25.268-08:00HF direct conversion receiverSince I recently got my HAREC HAM licence, I decided I need a radio for HF. So here are a description and some pictures of the current contraption I use to listen on the 40m band.<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjS0I8p1UcmMIeVnFL71Qp5UzS1_hHFeSAodJDx0m6UKObzt0kXBTmTzehEPtHiueX_pTF9aY88-BcZtIA98HBMkvHr8gmrFNOSsOL-HEygsG_99RzDbrPDbvxty4OMzijTXvkliZ6wJnaU/s1600/P2278690.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjS0I8p1UcmMIeVnFL71Qp5UzS1_hHFeSAodJDx0m6UKObzt0kXBTmTzehEPtHiueX_pTF9aY88-BcZtIA98HBMkvHr8gmrFNOSsOL-HEygsG_99RzDbrPDbvxty4OMzijTXvkliZ6wJnaU/s320/P2278690.jpg" width="320" /></a></div>
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjbOmtSVc2ukUZOgDTkaEdgm5UgWVCn5wQcoAxxbl_FrlXclgjXAOp9wqFwQBn_ad8Eih5Jk3PuWMTMAHsJprtr_enOien9UUW90rRcmN8G7o33JetPnSZkkJYwDT0KJYCxnc3cYMfVdzMA/s1600/P2278695.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjbOmtSVc2ukUZOgDTkaEdgm5UgWVCn5wQcoAxxbl_FrlXclgjXAOp9wqFwQBn_ad8Eih5Jk3PuWMTMAHsJprtr_enOien9UUW90rRcmN8G7o33JetPnSZkkJYwDT0KJYCxnc3cYMfVdzMA/s320/P2278695.jpg" width="320" /></a></div>
<br />
<br />
The RX part was inspired by the popcorn DC receiver mainframe published by VE7BO on his site <a href="http://www.qrp.pops.net/popDC.asp">http://www.qrp.pops.net/popDC.asp</a>. I used slightly different diplexer (similar to B variant) and created both filters with bistable relay switching circuit. ADE-1 from Mini Circuits serves as the main mixer.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh96SER6WN0DziRJT3w8nREHGNq3kEBsCPUJDze50iEOzWtBYzpq1qisjFVvJZKPX8kwDlVqAypU3ouhKhyphenhyphenDW3-JoHESrEBLxTkxeKLG8qylTowdY21kGqRUxRDiCqQV2nMBEoY8-i2UT__/s1600/P2018655.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="304" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh96SER6WN0DziRJT3w8nREHGNq3kEBsCPUJDze50iEOzWtBYzpq1qisjFVvJZKPX8kwDlVqAypU3ouhKhyphenhyphenDW3-JoHESrEBLxTkxeKLG8qylTowdY21kGqRUxRDiCqQV2nMBEoY8-i2UT__/s320/P2018655.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">DC receiver, groundplane construction,<br />
the switch was later replaced by relay</td></tr>
</tbody></table>
<br />
The receiver used to be controled by Arduino (with Diecimila bootloader to support eeprom flashing), but has been since replaced by much smaller cpu board holding ATmega644PA microcontroller running at 8Mhz on internal oscillator. This board connects to all controls, LCD and a DDS box, which is the source of RF signal for the ADE-1 mixer in the receiver. The CPU board also provides 5V regulated power to all digital parts.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiRuvfHlbD0ZRcC2amB8IZzvGERybGql4EyCTPwRu0n5jjlmkGgueIHTS56htMeeCoveFD1v5DemRgDHvyxpYgqu-AEMxhohLq9-lR-wQTsdLlCjq9HLV8J0orDi_enbIbVS5wm_7d-GPKv/s1600/P2228672.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiRuvfHlbD0ZRcC2amB8IZzvGERybGql4EyCTPwRu0n5jjlmkGgueIHTS56htMeeCoveFD1v5DemRgDHvyxpYgqu-AEMxhohLq9-lR-wQTsdLlCjq9HLV8J0orDi_enbIbVS5wm_7d-GPKv/s320/P2228672.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">ATmega644PA with pin headers, voltage regulator (upper right)<br />and SFH5110-38 IR remote demodulator (bottom left)</td></tr>
</tbody></table>
<br />
A sample of AD9835 was used as a basis for the DDS oscillator, together with a low pass filter based on a design by maxit91 (<a href="http://hem.passagen.se/communication/dds.html">http://hem.passagen.se/communication/dds.html</a>). The whole module is built in RF tight box to prevent RFI.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg6wtBEQiu8-u2UbOFOP2bgXx15DNTDNIFfWVSm9GTwUsuerbZJdaSZjIlfoM50qYGUxm66xN5EvgLVKnfbk1MlpO3CrzM0GHUPIYQH7q_4E4Fa85LUBqA_GOoeGr71einuidHyBsNi8_Gb/s1600/P2228677.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg6wtBEQiu8-u2UbOFOP2bgXx15DNTDNIFfWVSm9GTwUsuerbZJdaSZjIlfoM50qYGUxm66xN5EvgLVKnfbk1MlpO3CrzM0GHUPIYQH7q_4E4Fa85LUBqA_GOoeGr71einuidHyBsNi8_Gb/s320/P2228677.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">DDS is the silver box next to the knobs.<br />You can also see the placement of LCD ad CPU boards,<br />power switch, fuse and back ground plane with connectors.</td></tr>
</tbody></table>
<br />
Filter switching relay is controlled using couple of transistors by two of the ATmega's pins.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgM6oqk3JQ3RSzVdy9_zPZgdNrpxtzSpUyo8eR_slLh75QSeewcYgO2n-5huXJ45SrjLqZ7-U-eCRhdhDwzGff_1UYelCs6Z0d0GqZk-BYwn1SblASizNcbQr01gnHMq5Ok9c9nF24J_hwy/s1600/P2228676.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgM6oqk3JQ3RSzVdy9_zPZgdNrpxtzSpUyo8eR_slLh75QSeewcYgO2n-5huXJ45SrjLqZ7-U-eCRhdhDwzGff_1UYelCs6Z0d0GqZk-BYwn1SblASizNcbQr01gnHMq5Ok9c9nF24J_hwy/s320/P2228676.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Relay control board</td></tr>
</tbody></table>
<br />
There are four buttons, volume knob and rotary encoder for user input. Currently only volume, rotary and two buttons are used as the firmware still contains only very basic functions. It is possible to switch between CW and SSB filters and change the frequency (using 7 different steps from cca 1Hz to 1Mhz per revolution).<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi6PkrHwTmiVqjakNABwCnwb0y-kmhvW9agYK_7aA7yJwMHG646Idre6KxvBBRjHZu8wQovf9iopKuXrqIAoTC4RbGPfM0OA2_cTMFgJ30eOJh58tL2SAo6EKLPiFinq5dB0-SY5TyWY201/s1600/P2228669.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi6PkrHwTmiVqjakNABwCnwb0y-kmhvW9agYK_7aA7yJwMHG646Idre6KxvBBRjHZu8wQovf9iopKuXrqIAoTC4RbGPfM0OA2_cTMFgJ30eOJh58tL2SAo6EKLPiFinq5dB0-SY5TyWY201/s320/P2228669.jpg" width="240" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">The insides.. just before the new CPU board was installed.</td></tr>
</tbody></table>
<br />
I will publish some schematics as I draw them as most of the work was experimental and the circuit changed often.<br />
<br />
The current firmware lives at <a href="https://github.com/MarSik/HF-SSB-CW-direct-conversion-receiver">https://github.com/MarSik/HF-SSB-CW-direct-conversion-receiver</a> including the bootloader that I had to adapt from Sanguino (m644p port) and Arduino sources (Diecimila's bootloader supports proper upload of eeprom data and reports correct signature).<br />
<br />
In the future I'd like to use the free space I got by replacing Arduino to add CW transmit capability and about 5W PA.MarSikhttp://www.blogger.com/profile/04703143981787504455noreply@blogger.com0