Monday, February 8, 2010

JT65b Digital mode on 2M SSB

Over the course of the past year I've been working on getting my home VHF/UHF station permanently on the air. I've had various antennas up in temporary configurations, but never with any sense of permanence. Recently, while reconfiguring the workshop, I also reconfigured all my feedlines and radios. I now have a permanent 2m ssb radio, 2m 160w amp and 12 element yagi up around 25'.

Part of the reconfiguration also got me back on HF again, something that I've been missing since I moved to Colorado back in '04. With the big feedline re-shuffle I re-routed my 75m inverted vee up to the same radio that is the permanent 2m ssb station (Yaesu FT-847).

One of the main HF modes that I enjoyed was PSK-31. I really enjoyed watching the DSP work wonders with nearly completely in-audible signals. Part of the new station configuration included purchasing a Tigertronics Signalink USB soundcard/radio interface. This is a nice little unit that greatly simplifies the whole radio interfacing, in my case, eliminating the need for overly complicated wiring schemes.

While working PSK-31 one day it occured to me that now that I had this digital interface I could also try some of the new WSJT modes on 6m and 2m. Since I didn't have a 6m up in the air, 2m it was! This all happened during the weekend of the ARRL January VHF Sweepstakes, so it was a good time to test it all out.

Well, Saturday night of the contest weekend I listened on the meteor scatter calling frequency of 144.140, but I wasn't hearing any pings at all. I decided to leave the program running over night to see if I heard anything. In the morning I was very happy to discover that I had decoded a couple of pings! Wow, actual reflections off of meteors! Over the course of the next couple of weeks I didn't have much time to play, but this past Saturday afternoon I found myself on Ping Jockey talking to other folks. I actually heard some pings, but unfortunately had the WSJT program in the wrong mode. D'oh! Russ, K2TXB, asked if I'd like to try some JT65b over tropo, I was excited to try!

Off we go, I see Russ's signal and I start clicking buttons, quickly realizing that I don't know what I'm doing :) All the reading I had done was on FSK441, not JT65, so the sequencing was a bit different. Then, much to my dismay....WSJT starting crashing! Needless to say Russ and I didn't complete, but Russ was a great sport and gave me some private pointers that really helped me out. I was very appreciative that Russ took the time to elmer me, it really does make a difference, thanks Russ!

I'll skip over the saga of me getting WSJT to work, but it involved downloading the source code and compiling on mutliple machines. The bleeding edge is often a painful place to live. In the end I had a workable system. The "end" was about 11pm that evening.

Sunday morning 5:45 I wake up with hopes of actually completing with someone, I jump on Ping Jockey and to my suprise there are a handful of guys awake and ready to run. My first victim was VE2DSB, Dan up in Quebec, FN35hs. Dan wanted to try QRP first, just to see if we could do it. I figured with me being a complete amateur at the digital modes I would have failed completely, but to my surprise I was able to see his signal on the waterfall! The QSO went very well, no issues at all (other than one operator error, clicked the wrong button). A few minutes later we had a QSO in the logbook! Dan then told me that he was only running 15w into a fairly modest antenna!

Here is a shot of the spectrum with the messages added on top in red.

15 Watts into a 12 Element yagi, and we were able to work each other over a 285 mile path! It's absolutely amazing what can be done with these digital modes.

My next step is to sucessfully work someone on FSK441. I've had some decodes, but never enough to actually make a contact. Saturday, during one attempt, I had several folks out in the midwest report hearing *my* pings, but I never heard any in response. Part of the station improvement that will happen shortly is the addition of a SSB Sp-2000 pre-amp that will be mounted up near the antenna. I just need the weather to cooperate and give me a nice 50-60 degree Saturday afternoon. Wishful thinking?

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