“Success” for the GCARC Field Day satellite station has always had somewhat of a low bar – if we made the one contact needed for the 100 bonus points we declared success and quit, finding that getting any additional satellite contacts weren’t worth the effort. Normally satellite bands are pretty open with only about a half-dozen stations operating, but on Field Day the entire passband of most of the operational satellites was full. Since satellites have a fixed power budget, that budget is divided among the current users and when there are dozens of users each signal is considerably weaker than on non-contest days. Add to that the issue that only two of the six Chinese XW satellites appeared to be functional and that most of the FM satellites that only permit one QSO at a time are unusable and the operational landscape of the station was pretty limited. Nonetheless this was our most successful Field Day ever. It also held the single most memorable QSO in the 58 year amateur career of your humble author, as we’ll detail below.

We made several significant changes in the Field Day infrastructure this year. Last year the 3D printed az-el rotator that N3PUU built from the SatNOGS plan didn’t have sufficient torque to elevate the antennas to a full 90 degrees – we had to stop at 75 degrees which probably limited coverage on really high passes. For this year Frank replaced the stepper motors with larger units that easily handled the LEO-pack antennas that we use for this station.

Another change improved the receive signal strength. Previously we placed the SDR receiver in the operating tent and fed it with coax from the antenna which created line loss particularly at 435 mhz that some satellites use for the downlink. This year we got a little smarter and mounted the SDR radio at the rotator, connecting it to the PC with a 30 foot USB cable. That eliminated a lot of line loss and gave stronger signals.

Getting the Bonus Points

There were several good satellite passes on Saturday morning before the event began so we were able to dry-run the new configuration and make several contacts that demonstrated that the configuration worked. But unfortunately there were no passes after the 2 PM start for another 3-1/2 hours, so the satellite team spent the time showing visitors around the clubhouse. The first few passes were unsuccessful but finally we were able to get the one QSO that guaranteed the 100 bonus points. The pressure was on – apparently every other station shut down to eliminate any interference to the potential satellite contact which appeared to lead to almost every operator lining up in the dark outside the satellite tent peering in at the hapless satellite op who finally managed to score one QSO.

A confounding factor was that the uplink transmissions on RS-44 (up on 2 meters, down on 70 cm) sometimes were interfering with the downlink, making it difficult or impossible to find the uplink signal. This didn’t happen predictably and I managed to suck in Mark, WM2Y at around 10:30 PM to try to solve it. After some experimentation we found that the interference seemed worse when the antennas were aimed north, and it was also worse when they were elevated than when they were horizontal. We tried adding some ferrite beads to the SDR feedline which didn’t seem to do much good, but the interference was mild on a later RS-44 pass and we were able to work a few more stations before quitting around midnight.

There were some good passes on Sunday morning so based on the previous night’s success I came back to try for more QSOs. None were particularly successful, and at one point N3PUU, K2QA and I were stting in the satellite tent and decided to listen in on the upcoming pass of the International Space Station’s FM repeater. FM satellites are always a madhouse since they’re easy to access with simple ham equipment and only allow one QSO at a time, so for Field Day they’re almost unusable. But we thought it might be amusing to check it out so we tuned in and let the satellite software spin the antennas and tune the radio.

Then We Heard NA1SS…

But our attention perked when we hear the call of one of the stations responding – it was NA1SS which is an astronaut on the ISS. One of the astronauts was actually operating Field Day from the space station! The QSOs were surprisingly orderly – everyone seemed to realize that interrupting or stepping on others would result in nobody getting their ISS QSO. We gave a few calls but weren’t successful, even in hearing ourselves through the repeater. I decided that somehow I didn’t have the radio PL tones configured correctly, or there was some other problem that was preventing us from being heard.

In spite of that I decided to give it another try. Mike N2WOQ sat in to listen on the next pass when NA1SS was still operating. I tried a few calls but never heard myself on the repeater. Then near the end of the pass I took one more shot – “Whisky two mike mike delta, 7A Southern New Jersey”. Immediately he responded and we traded modes and sections (he was “1A, DX”, which is certainly appropriate for a station in space). It was over in about 30 seconds but was the most memorable QSO in my 58 year amateur career. Fortunately I had turned on the IQ recording on the SDR and was able to extract this audio recording of the QSO.

One factor that may have contributed to the success was that I had configured the radios (RX and TX) to follow the Doppler frequency shift through the pass. By the end of the pass (which is when we got the QSO) the Doppler-adjusted frequency was 3 khz off from the published freq. This meant that anyone who hadn’t adjusted their transmit frequency was 3 khz off, which may have kept them from keying the repeater and allowed me in with less interference. A lucky break.

For next year we’re going to try to simplify the cabling going to the antennas – this year we had to go thru numerous adapters to match the N connectors on the LEO pack beams with the PL-259 on the IC-7100 radio used for transmit and the SMA connector on the SDR Play receiver. Next year we’ll have custom-made cables for everything. We’ll also try some additional filtering on the SDR to eliminate the occasional interference on the mode v/u passes. And maybe we’ll work the ISS again…

73 de Jon WB2MNF