Hi!
I wavered on whether I was going to get this radio straight away, after the fiasco (related to FM satellite operation) the Alinco DJ-G7T was last year. I didn't want to get bitten by a radio that was supposed to be capable of full-duplex operation, but fall short like with the DJ-G7T. After some thought, and after yesterday's hamfest, I drove over to the local HRO store to see if they had any in stock. At mid-afternoon, HRO still had 3 on the shelf at this store. I decided that, if the TH-D72 is the true successor to the TH-D7 including the cross-band full-duplex capability for FM voice satellite operation, I'd take the plunge. I bought the radio and the only option they had for it in the store (cigarette-lighter cable, compatible with several other Kenwood HTs including the TH-F6A I purchased a few weeks ago).
I charged the battery last night, and cleared some time this afternoon to go out to my favorite city park to try it out. Not having used a Kenwood HT on the satellites except for the TH-F6A as a receiver, I read through the manual to make sure I had it set up for FM satellite work. I looked at a few parameters I felt would be useful:
1. Transmit with VFO B, receive with VFO A. VFO A has better sensitivity than VFO B, so why not go with that? There is no restriction on which VFO can be the transmitter for this radio.
2. Audio balance. I set that all the way to VFO A, since I wasn't interested in hearing VFO B. I could see with the S-meter if anyone else was transmitting on the satellite uplink, and then rebalance the audio if necessary to hear it.
3. Squelch. Open all the way on VFO A, tight on VFO B.
4. "DUP". This was a new one for me, not being familiar with the TH-D7 in the past. Once I figured this out, turning it on for my transmit VFO (VFO B), I was able to hear audio from VFO A whether or not I was transmitting on VFO B.
I had to get a plug adapter to use my normal audio cable/splitter setup for an earpiece and my audio recorder with a Kenwood HT and its smaller speaker jack. I already had one for my TH-F6A, and it worked fine with the TH-D72A. I made sure tuning steps on both bands for both VFOs were at the smallest step (5 kHz), and that I had VFO B set for high power (5W).
I started with the AO-27 pass at 2102 UTC. A very high pass here, with maximum elevation of 80 degrees. I worked 7 stations in 7 minutes, and received good reports on my audio through the satellite with the new radio. The only issue I had in hearing the downlink wasn't due to the radio - I had to move the antenna around as it passed over my head, and there was a moment or two where the downlink audio was less than ideal. I had to switch VFOs when tuning the receive VFO, something I don't have to deal with on my IC-2820H mobile radio or when I use memory channels in a non-full-duplex radio, but that was not a problem.
The second pass I attempted with the TH-D72A was on AO-51 around 2322 UTC. This was also a high pass, with maximum elevation of 63 degrees out here. I had a little bit of difficulty hearing the satellite in the first minute or so of the pass while transmitting, which could have been related to how I was holding the antenna (Elk log periodic). I found during this pass that I had to twist the antenna to clear up any receive issues while transmitting. I think I might have heard the slightest desensing during a couple of my transmissions, but that could have been related to how my antenna was oriented toward the satellite. I logged 10 QSOs on the AO-51 pass, which wasn't bad for all the activity on there.
As I posted earlier and said on the air, the TH-D72A is the real deal as a dual-band HT for full-duplex FM satellite operation. It does what the DJ-G7T could not do, and I didn't even have to use the expanded manual on the CD that came with the radio to get it set up for satellite work. I also set it up to work on APRS, which took little time to do. I have not tried it with a computer, to see if it will work as N8MH asked earlier. Packet is actually something I was not very interested in for this radio - FM satellites first, APRS next. The radio's GPS took only a few minutes to pick up signals when I first activated it.
I do not have test equipment to quantify how well the TH-D72A's receiver is and how it compares to other radios. From playing with it last night and today, I know the receiver is on par with the IC-2820H I usually run on FM birds. Excluding transmitter power, the only thing the 2820 has over the TH-D72A is its separate knobs for each VFO. It also compares favorably with the sensitivity of my IC-T7H HT - the radio I've used on satellites from outside Hara Arena in Dayton (my other radios' receivers get swamped with intermod there, but not the IC-T7H). I will have to test it in a high-RF area like that at Dayton, to see if intermod plays havoc with the weak satellite downlinks.
I'll work with this radio more, to get more familiar with it and possibly work it into my demonstrations. I will eventually get around to hooking it up to a computer, and seeing what I can do with packet and APRS. If I'm not careful, I might even go as far as having an all-Kenwood HT station for the OSCAR Straight Key Night in a few weeks (TH-D72A as CW transmitter, TH-F6A as receiver).
73!
Patrick WD9EWK/VA7EWK http://www.wd9ewk.net/