Non-Terrestrial SOTA Operations

Greetings, all.

I’m thinking about investing into adding a satellite capability to my portable kit, and it got me wondering if anybody has gone about conducting a SOTA activation using one of the amateur radio satellites up in the heavens? How did it go? Were the QSOs accomplished on a schedule? What equipment was used?

Or better yet, has anybody attempted a SOTA EME contact? With the JT modes out there, and some advances in battery technology, I think this could be barely possible, with sufficient luck and labor, to complete a SOTA QSO using the moon. It would probably take a decent portable VHF/UHF radio, a good receive preamp, a brick amplifier, a bunch of batteries, a computer, and a couple long yagis on a tripod. It’s probably best to complete such a QSO on a schedule, with the moon at the horizon (to take advantage of ground gain, and to also simplify the antenna elevation issue). My assessment is that it would be possible to do this, but challenging.


Nate N0PCL

The following stations have notes in their logs saying various AMSATS were used.

KL7R <<<<<<<< One of the few Alaskan QSOs

Thanks, Andy. I’ll look these people up.

I was at Norfolk Island with the VK9NA expedition in 2011. We used a 19 element 39’ yagi on 2m, a TE systems amplifier capable of 300w output and a rotatable mast, with antenna elevation controlled by ropes. The driver rig was an FT897D. This setup was adequate for JT65 operation for EME. I think the strongest incoming signal was at -14 s/n, the weakest decoded was at -28. At the other end our signals were in the same range or lower.

And we used locally available mains power.

If you start subtracting a few db for power output, a few db for shorter antennas, a few db for cable losses, you rapidly sink below the noise for Rx and Tx.

I think 100w with a pair of small yagis (10 or 12 elements) would make the grade provided a 4 yagi 1kw station is at the other end. Wayne VK5APN has made a number of “QRP” eme contacts on 2m, ie. 100w and a pair of yagis, with elevation control.

the VK3UM (SK) software, or similar from GM8JJJ (?) will allow you to plug in your antenna, cable, power, preamp NF etc and Calculate how a given configuration will work, given the parameters of the station at the other end.

We had a bit over 100 contacts in 10 days of eme operation. Not many stations with less than 4 yagis worked us. With only 2 x 10 el, I think only 4 yagis and more, plus preferably 1kw or more at the other end, was feasible. Otherwise the path losses just kill the signals.

Add the power requirements for JT65 continuous transmissions 50 seconds at a time, this is definitely serious battery territory. CW would require a lower average power requirement, but about 10 db more antenna gain or output power. The more recent versions of JT65 may give an extra db.

Some photos of our setup are on my flickr site, Andrew Davis’s albums | Flickr and look for 2011 Norfolk Island.

73 Andrew VK1DA VK2UH

Using the amateur satellites could actually be pretty useful now that I think about it. Imagine using 2M APRS from a remote summit to self-spot. That could be challenging without a digipeater nearby, but if you have a favorable APRS satellite pass during your activation then you could go through the satellite. Or bounce a packet through the ISS to self-spot. Talk about bragging rights!

I’ve never worked the amateur satellites, but the problem I can see would be the timing. You have to have favorable passes occurring your activation, and specifically, while you are on the top. When you factor in the hiking time and other variables that could get tricky.

The equipment needs shouldn’t be too great though. Maybe something like the Arrow dual band yagi with duplexer, or a homebrew two- or three-element 2 M yagi, with something of similar size on 70 cm. Program in split frequencies and run both antennas into the same rig through your duplexer, and away you go.
Brandon, N6BSC

It has always puzzled me that contacts via repeaters do not count for SOTA credit, but contacts via satellite-borne repeaters apparently do count.

Walt (G3NYY)

Terrestrial repeater operation is trivial. Satellite operation is not trivial but quite involved in comparison.


I think this is based on the expectation that comms via a satellite is difficult and requires lots of equipment on a summit to do it. With more and more FM repeater satellites going up all the time, that is perhaps no longer the case.

I tried with a chinese HT and an Arrow hand held antenna from Australia about 5 years ago, got in first time from my garden, worked three stations and then afterwards never bothered again.

While satellite usage will NEVER be as simple as ground repeater usage of late the possibilities have increased and the complexity of using satellites reduced.

Perhaps it needs to be re-considered?


Aiming a hand held yagi while buffeted by wind or balancing on loose rocks doesn’t strike me as an easy option, and you may need more than one pass of the satellite(s) to qualify the activation.

We are considering a few tweaks to the rules at present, this also could be discussed.

Understood, but any bad weather conditions can make an activation more difficult - that problem doesn’t only apply to a Satellite QSO. A sturdy tripod to mount the antenna on would help a lot of course.

Another thing to consider is the distance of the contact, where using a terrestrial repeater may only be 10-20 miles away getting a signal to a satellite (especially soon after POA or just before LOS) can be a lot further.

You mean both of them? :wink: There are currently 2 birds workable via FM voice: SO-50, that was launched in 2002, and AO-85. There is also LILAC-2, but the transponder is rarely available. There are 2 APRS sats that are workable - ISS (currently on UHF) and NO-84 that is usually operational.

I can’t remember the last time I had terrestrial repeater moving on me, much less fast enough to need to deal with doppler.

I’ve tried for satellite qso’s a couple of times from a summit, but I had more problems with QRN/QRM up there than from my QTH. I don’t think I would depend on Satellite qso’s for an activation. Perhaps if I had a whole day to spend on a summit to spend napping between the 10-12 minute satellite passes or if the summit was in a very rare grid square. No, I would still take the HF gear.

Spotting through ISS would be awesome. Of course, that requires an I-Gate to get your message. From where I’ve operated, that has been something less than certain. Timing arrival to a summit at the precise moment of an ISS pass would also be another consideration.

–Chris K7TAB

There was a recent batch of Chinese (XW) satellites and the FOX series satellites with 2m-70cm transponders on them, it seems I was mistaken with the XW satellites I had thought they were using FM transponders but in fact they have linear ones. It appears LILAC-SAT2 is the only current Chinese AR FM satellite in orbit. I Know you mentioned FOX-1A (AO85), but isn’t FOX-1B now launched, if not it should be very soon. The Fox series up to 1D have FM transponders.

In general there are still a greater number of amateur satellites to be used, than when the rule was brought in however I would agree that using CW or SSB through a satellite is more difficult than FM.

It is my understanding that the ISS can be worked using an FM hand-held. Seems quite trivial to me!

Walt (G3NYY)

Well Walt, you stand in your garden next time there is a pass in range of your QTH, with a hand held and its own aerial and tell me how much success you have.

Just make sure your 5W into a duck is louder than all the QRO monsters in Europe with antennas tracking the satellites running KW ERP. And do tell how well you get on any pass where the satellite passes over Southern Europe first.

Don’t forget, you have about 12mins to work 4 QSOs in competition with ALL those other people.

When Es’hail 2 goes up we may have to reconsider the rule. Till then it’s anything but trivial.


ISS has a packet digipeater. FM voice is possible - IF the astronauts are on the air, you may be lucky and get through THAT pileup and get a contact with one them. I’m unaware of anyone that has done that in the last year - other than through telebridge contacts with the education program for schools. Good luck timing that with a Summit!

Nope :frowning: It’s been scheduled a bunch of times. It was scheduled for this month, but has slipped again to Aug 29. FOX-1E is currently scheduled for December 2017. The problem here is that AMSAT payloads are not a priority. They’ll go up when there is room for them and they will be the first to be booted for a more important payload. BTW, Fox-1C/Fox-1D: TBD

I think the CAS folks are sending up some more FM birds too. Hopefully, they’ll get them into a good orbit, the equipment works, and is regularly available (unlike LILAC-2). BY70-1 didn’t make it into the correct orbit - It was launched in December 2016 and re-entered February 18.

Two other differences from terrestrial repeaters that we failed to mention were power and polarity. These little 10cm cubes are typically very low power (500 mW EIRP). Working them also requires matching their changing polarity. This makes using the tripod rather difficult. This is especially true of the arrow antenna because you have to twist it 90 degrees when transmitting because your transmit antenna is crossed with your receive.

Linears add some complexity that can be overcome with more hardware (2 radios + computer). There is one bird that is V/U (FO-29) that can be worked semi-duplex. It’s still not easy. Full duplex is always better with satellites.

I can’t even imagine trying to work a satellite, portable, using CW through a linear. You would have to have one hand on the VFO, one on the key, and one on the antenna! I only came equipped with two hands.

–Chris K7TAB

HaHa - a good reason for a muti-op activation!

I know we may be going off topic a little here, but I think I heard talk of a satellite being built that will use one of the assigned HF satellite frequency ranges for its downlink - not sure if that was on 10m or 15m? I believe some of the early satellites used HF? - I guess doppler is less of a problem at HF frequencies?


Yes, I remember hearing Oscar 6, 2m up, 10m down. Ran from 1972 until 1977. I don’t recal working through it, though it is a while ago now…


Yes, the lower the frequency, the less it is effected by doppler.

The only two, that I’m aware of, that use 10m are
NO-84: 28.120 PSK31 uplink, UHF downlink still needs doppler adjustment (and special software to do it)
AO-07 when in mode ‘A’ is a 10m downlink. Not sure how often mode ‘A’ is available.

–Chris K7TAB

No-one does as it switches mode randomly.


O7 must have been very well built. I used it in the 70s when its battery was still operational. That seems a long time ago. Yes, it was…