[amsat-bb] Another satellite-receiver option

n3tl@bellsouth.net n3tl at bellsouth.net
Mon Jun 8 06:07:19 PDT 2009

Hey everyone, 

Over the weekend, I had a chance to do some more testing and experimenting – this time, with a Kenwood TH-F6A HT.  My sincere thanks to Ed, N4ALE, who loaned me his TH-F6A for the weekend. I picked it up Friday afternoon and returned it Sunday afternoon, giving it a pretty good workout in the interim – well, part of it.
I can’t tell you how it performs on AO-27, AO-51 and SO-50 because I never tried it with any of our FM satellites. In fact, I never keyed the radio’s transmitter. Instead, I focused on its receiver.
The TH-F6A proved to be a capable receiver for use on AO-7, FO-29 and VO-52. If you have an all-mode radio that will operate in CW and SSB on the UHF and VHF bands, you can use the HT as your receiver for a full-duplex station that will work our linear-transponder satellites. For the record, I believe the current-production all-mode transceivers that are NOT full duplex include two Icom models (IC-706MKIIG and IC-7000) and three Yaesu models (FT-817ND, FT-857D and FT-897D). Anyone with one of these rigs and the Kenwood can do what I did last weekend. Just add antennas, or a duplexer and a dual-band antenna. There are plenty of workable options, including a good number of homebrew antenna designs to consider.
I started out Friday evening just listening because I discovered I needed an adapter to connect my headphones to the receiver jack on the radio, which takes a 2.5 mm connector. Full-duplex contacts in SSB wouldn’t happen until I had that, so I connected my Elk and configured the radio’s B-Band to receive SSB in the 2 meter and 70 cm pass bands. It’s easy to set up, and the fine-tuning feature permits tuning steps in CW or SSB as low as 33 Hz. I chose 100 Hz, which worked well.  Switching from CW to SSB took only a few seconds. Through the evening, I copied AO-7 on multiple passes to the east and west of my location, and had reception below 4 degrees at the end of the passes, which was encouraging.
Just before 03:00 UTC Friday evening, I had a VO-52 pass that reached a maximum elevation of about 70 degrees here. I copied practically the whole pass, hearing K8YSE work AA5PK and KB1PVH, and also clearly copying CW from W8IJ. Here’s the fun part about that pass – I was standing in my driveway, using a Diamond SRH-789 telescoping whip for an antenna. Having the ability to copy pretty much the whole pass with just a whip helped me to see that the TH-F6A probably would do OK as a satellite receiver. 
After picking up the headphone adapter I needed Saturday morning, I started working passes. Using an SMA-to-SO239 adapter, I connected the HT to the Elk using a Diamond duplexer. I used either a Yaesu FT-857D or a Yaesu FT-817ND as my transmit radio. The earliest afternoon pass of AO-7 hit 3.8 degrees maximum elevation here, but I heard my CW signal and called CQ a few times with no answer. The next pass of AO-7 was well over 30 degrees here, also to my east. I worked N3TE in CW, then switched to SSB and moved up the pass band for a voice contact with K3SZH. By then, AO-7 was descending to my north, so I switched back to CW and started calling CQ – primarily to see how long I could hear myself through the HT on the downlink. I was thrilled when K4YYL called me. When we finished that contact, AO-7 was at 2.6 degrees elevation according to the computer. 
I should mention here that I was manually tuning for Doppler throughout the weekend, which also gave me a chance to use various software packages as my “guides” for finding myself at the start of a pass.  Ham Radio Deluxe’s Satellite Tracker, Orbitron and SatPC 32 all proved very helpful. After launching one of the programs and getting the Doppler tuning on screen, I just followed their lead and found myself quickly, then stayed where I needed to be – evening tuning up and down the pass band to call others I heard. 
On the next pass of AO-7 (the last of Saturday evening for me), I worked K4YYL again – this time in SSB, and this time using an FT-817ND at 5 watts out for my transmitter.  Think about that – a fully functional all-mode satellite station that I could fit in a day pack with room to spare!
FO-29 later Saturday evening was frustrating only inasmuch as there weren’t many folks around. The first pass here hit less than 20 degrees maximum elevation to my east, and I called CQ in CW without a contact.  The next pass was about 70 degrees maximum elevation, and I talked to myself for the first 2/3 of the pass before switching over to VO-52, which was also in range at about the same time. K9QHO and I had a nice contact in SSB.
Sunday morning, I only wanted to get some contacts on FO-29 because I promised to return the radio that afternoon. I worked Dave, W8IJ, and Leo, W7JPI, in SSB. Seven contacts in all, covering all three CW/SSB satellites and both modes, and all of them using the Kenwood HT as my receive radio. I could have made additional contacts if the satellites – especially FO-29 – had been busier on the passes I worked. 
A lot of AMSAT members do demos for radio clubs and other groups from time to time, and I decided to post this report on the TH-F6A with that in mind. I know that many who do demos often schedule them to coincide with passes of the FM LEO satellites – and there’s nothing wrong with that. But AO-7 and AO-51 often make evening passes, for example, that are within 30-40 minutes of each other. It occurs to me that letting folks hear satellite contacts in CW and SSB over a satellite that has completed more than 156.000 orbits might be pretty cool – especially when you can note that anybody in the group who has an HT like this one and an all-mode VHF-UHF radio can work AO-7 with the right antenna(s) and a little practice. 
I looked around on the Web after returning the HT to Ed, N4ALE, and learned that Alinco, AOR, Icom and Yaesu all offer HT-style receive-only radios that are all mode, like the TH-F6A. I suspect any of them could serve as an all-mode satellite receiver, too, although I haven’t tested any of them.  I hope to have that chance moving forward. I like the TH-F6A because it also can double as a full handheld station for the FM satellites, albeit in half-duplex. I know that’s not the recommended way to go, but I and many others are, collectively, proof that it can be done effectively and without totally wrecking a pass. I hope all the manufacturers soon will have at least one full-duplex-capable HT in their lines – and that those radios will have all-mode receive on at least one band, like this Kenwood. 
In the meantime, I encourage those of you with this little radio to experiment with it as a receiver for AO-7, FO-29 and VO-52. I suspect you’ll be satisfied with its performance.
73 to all,

Tim – N3TL

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