I recently got hold of a motorized roller inductor that is made PROPERLY. This is a MIL-SPEC unit that has been on stock for many years. It features a silver foil that is rolled on to a ceramic former, pretension, a shortcut cylinder that prevents eddy currents and arcing on the unused coil section under QRO operation. Due to that the unused coil is shorted and that the shorting is not a single turn, that the foil is wide, this coil has a very high Q.
F5OEO has recently written some code to transmit a SSB signal using just the hardware in the Broadcom SOC chip on the Raspberry Pi. You can find more info on this link http://www.rtl-sdr.com/transmitting-fm-am-ssb-sstv-and-fsq-with-just-a-raspberry-pi/
I tested the code on my RPI on 6m via a cable connection. It worked OK. If you look at the S-meter you can see that the envelope is constant. This is due to that the RPI has no way of modulating the envelope so the software actually modulates frequency. It is kind of constant envelope SSB.
Below you can see what the signal looks like. (This is received on a SDR via an attenuator). The signal is a bit too wide. However cool test.
If you want to test the code yourself you can check it out over on F5OEO at github https://github.com/F5OEO/rpitx
Warning: do not connect the RPI GPIO output running this code to an external antenna without a bandpass or lowpass filter and a valid amateur radio license. Never transmit any signal outside the amateur bands.
I just got myself a new roller inductor. This one is designed on the principle of a silver foil that is rolled away from and onto a ceramic form with guides for the silver form. The ceramic coil forms the coil. There is a large shorting cylinder that the unused silver foil is rolled onto. The effect of this is to significantly increase the Q of the inductor. For high power QRO applications there may either be arcing from the end of the unused part of the coil or heat loss in this part of the coil. How the unused coil is completely shorted with an inner conducting cylinder and the unused part of the coil has no flux thru it.
Here is a review of SDR radios currently on the market in the low cost segment: http://www.rtl-sdr.com/roundup-software-defined-radios/
I am back from the megalocation at CR3L Madeira Island after working CQWW SSB with the R25 RRDXA team. It was a great weekend and we achieved good run rates however our targets were set at a higher QSO number. Since CR3L is in AF zone 33 we worked three pointers both to Europe and US and got a good score. That was fun. Claimed score looks like we will be around number 9 worldwide (a bit above 15M points). The CR3L Madeira station is located at Santana in a mountain side on Madeira overlooking salt water. Thanks to the team! Ops: DF4UM, DH4JQ, DJ5KW, DJ8VC, DL1EK, LB3HC . Stay tuned for 2013 events.
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| Claimed #9 WW score in CQWW 2012 contest from CR3L (Madeira) | LB3HC in the foreground and DH4JQ in the background (we are working pileup) | DF4UM in the foreground and DJ5KW in the background (working pileup) |
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| DH4JQ on rig A | DL1EK in the foreground and DL8VC in the background (working pileup) | N1MM logger |
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| RIG B | Weather changes fast. Here the shack and the lower antenna in fog! | The team after the contest |
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| The 80m vertical | The 10m 5 el tower is “adjusted” by DL8VC! | The lower Threebander and 160m ant |
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| Ready for takeoff from Madeira Island | Approaching coastline from flight over Atlantic Ocean | On the way back to mainland Europe |
I recently needed a new CW keyer with Winkey compatibility for use with my N1MM logging setup. K3NG has written some nice keyer code that I compiled and uploaded to one of my Arduino UNO boards that I had laying in the shack (if you want to try it, you need the latest – above 1 – version of the Arduino “IDE”). Below you can see some pictures from making the prototype thru to ready made keyer with USB interface and adjustable speed button. I did not install the memory buttons, as I control the CW keyer via USB from N1MM or Hamradio Deluxe. It works very well with my Yaesu FT-450D but instead of the UNO I will eventually use a Mini Pro board with the Atmel Atmega 328. You can see more info on K3NGs site http://radioartisan.wordpress.com/arduino-cw-keyer/#comment-3255
Below is the schematic (remark: full credit is given to to K3NG!). I have modded the design for my own needs. Instead of the 2N2222 I use a TTL tolerant FET of type IRLIZ44N to drive the keyer output. Then I don’t need the 100 ohm resistors in series. I also did connect a piezo tweeter directly to the CPU without using the 2N222 transistor. It works OK. However, the sound of the piezo tweeter is not the best in the world. Finally, as mentioned above, I did not install all the buttons. I installed only the command button to save space. There is a need to do a small mod on the UNO hardware due to some reset issues. For that I will have to add another button that needs to be pressed when I want to upload code.
I also needed a CAT interface. It is possible to use a FTDI chip for this task, however the signal levels need to be transformed to +/- 12V. This I solved with a MAX232 board that I had laying around in the shack. So now I have a CAT interface that is compatible with Win XP, NT, 2000, 98, Windows 7, Windows 8 etc since the FTDI chips are widely supported. It looks like … but works like …
Edit 15. April 2015: since last time I also operated Russian DX contest from SJ2W. Good results. We expect to be among the top stations in Europe in our class.
Edit 11. February 2015: since last time I have been operating from SJ2W in CQWW SSB and there will be additional images and writeups posted from later visits.
I went to SJ2W in northern Sweden in May 2013 to work the WPX DX CW contest with SM3WMV Micke, SM2LIY Pelle, SM2XJP Peter, and SE2T Kurt. The QTH is fantastic! Several kms to the nearest neighbor, flat terrain and a very good antenna installations. Stacks on 40, 20, 15 and 10 as well as 4-SQ on 40m / 80m. I have posted some pictures below. Click on the pictures to see comments for each picture. Stay tuned for more info!
It is often problematic to find a current list of DX clusters. Many lists exist on the Internet but few are updated. Also, lists in logging programs like Ham Radio Deluxe are often very old. I have found that it is best to go to the official DX cluster website and take a look at the current list.
