Working F0-29

Now that I have worked an FM satellite (in my case SO-50) the next challenge was to try a SSB satellite.

The basics would be the same I figured, except I would need to use my Yaesu FT-817. In fact, all I needed to do was to switch rigs and take into account that I would be needing to run to 817 off my 7 a/h SLAB, which I would need to slip into a spare camera bag so I could carry it over one shoulder.

The battery is in a camera bag hanging on my left side, and the FT-817 is slung around my neck (I knew the strap would come in handy some day).

So that I could work the satellite single handed out in the field without the aid of computer software, this is what I did:

  1. Set the rig into split mode
  2. Set VFO A to 145.960. This is the uplink.
  3. Set VFO B to 435.840. This is the down link
  4. Make sure the antenna connection is set to the front connector on the radio
  5. Keep the radio set to VFO B

When I saw the satellite is within range (using Satellite Explorer on my PC), I went outside and pointed the antenna into the rough direction of the satellite’s approach. This was roughly north. Then I put out a call (the radio switches to VFO A automatically when the PTT is activated but returns to VFO B when it is released. Then I immediately began tuning down the band to listen for replies.

Sure enough, I heard Wal VK4CBW, George VK2WEL and Geoff VK2ZAZ. I had a very satisfying QSO with them, but it was challenging having to continually alter the receive frequency by hand during the receive cycle while altering the direction of the antenna to take into account changes to direction as well as height, all at the same time.

Next is to think about improving my operating setup, perhaps with some form of automatic tracking capability.



Working Satellite SO-50

One aspect of amateur radio that I am enjoying lately is working the FM satellite SO-50. To do so I use my Boafeng GT-3TP dual band hand held and an Elk log periodic antenna that I have mounted on a camera tripod.

My basic satellite communications setup.

SO-50 carries several experiments, including a mode J FM amateur repeater experiment operating on 145.850 MHz uplink and 436.795 MHz downlink. The repeater is available to amateurs worldwide as power permits, using a 67.0 Hertz PL tone on the uplink, for on-demand activation. The repeater consists of a miniature VHF receiver with sensitivity of -124dBm, having an IF bandwidth of 15 KHz. The receive antenna is a 1/4 wave vertical mounted in the top corner of the spacecraft. The receive audio is filtered and conditioned then gated in the control electronics prior to feeding it to the 250mW UHF transmitter. The downlink antenna is a 1/4 wave mounted in the bottom corner of the spacecraft and canted at 45 degrees inward.

The Elk was loaned to me by Wal, VK4CBW, an avid satellite fan who lives down the road from me. The antenna is basically a held-held job but I do find it gets a bit heavy after a while, hence the tripod.

Today SO-50 was within range at 4.56pm, so I put out a call and was answered by Roy, VK4ZQ, from Nundah in Queensland. And although Roy isn’t that far from me, the satellite is. The apogee height is 665km, which means at its furthermost distance from the earth, it is 665km away. Not bad for a two-way FM contact.


Better antenna for satellite work

Having worked my fist ‘bird’ with a hand-held, it was time to take the next step and try using a better antenna. The ubiquitous ‘rubber duckie’ has been said by many to be nothing more than an eloborate ground; it’s certainly a compromise antenna designed for simplicity and basic functionality at best.

Wallace, VK4CBW, suggested I try working SO-50 with a gain antenna as it would improve transmission and reception markedly. He offered to lend me his Elk hand-held antenna.

This antenna is a log periodic cut for the 2m/70cm bands and is only two foot long – perfect for satellite work.

I assembled the antenna (it comes with the elements all colour-coded for easy assembly) and put out a call the next time the satellite was within range. Bob, VK3MQ, replied and we had a superb, short, QSO. I was delighted as the distance between us was 1,346 km (836 miles). Not bad for an FM contact on simplex.


Next I worked Cam, VK4FAAJ, who was using a hand-held coupled to a home-brew yagi he made from a tape measure! Nice copy too, even though he was in my neck of the woods.




Working the satellites

I always wanted to work the satellites as there seems to be something mystical about them. They aren’t called ‘the final frontier’ for nothing.

After talking to Wallace, VK4CBW, it became apparent that this would be quite feasible with a dual-band hand held transceiver and some satellite-tracking software on my computer.

My Boafeng GT-3TP would do fine so I downloaded and installed gpredict into my Surface Pro 4.

I proceeded to monitor my satellite of choice, SO-50, which I chose because it is an FM satellite. Wallace helped program in the receive and send frequencies into my hand-held; receive frequencies starting at 436.805 and progressing down at 5khz intervals to 436.780 would be needed to take the Doppler effect into account. Transmit frequency remains at 145.850.

screenshot-1   As the satellite came within range I headed outside and turned on my hand-held, with the squelch turned right down. Pointing the rubber-duckie antenna towards the ground, I put out a call .. and listened. Turning this way and that, I repeated the call until I heard Wallace reply.

I had made my first contact. The interesting thing about this was that his shack is only some 300m down the road from my shack, but we were communicating via a satellite in space. The pass only lasted around eight minutes or so; brevity is the name of the game here.

My next attempt would be with an Elk antenna, a specially-designed four-element log periodic antenna that Wallace will lend me.