Hi!
Another day, another radio to try on AO-85. I woke up early, and decided to try another HT on a high AO-85 pass starting at 1350 UTC. I wanted to see if it could work the satellite full-duplex. The radio, this morning: the Puxing PX-UV973. After working AO-85 with it this morning, my (low) expectations were met.
The Puxing PX-UV973 has been on the market a couple of years. It is supposed to handle cross-band full-duplex operation. This radio is still in production, and I picked mine up from Amazon for about US$ 78. It is less expensive than the other radios I have tested so far for full-duplex operation on AO-85, and it shows.
First, the simple question. Can the PX-UV973 work AO-85 full-duplex?
Yes, more or less.
The radio comes with a duckie antenna, and a 7.4V/1200mAh battery pack. The battery pack is smaller than the standard packs supplied with the other HTs I have tested so far. It is also a little bit smaller than the other HTs. As with the others, I did not program any memory channels to work AO-85. I used the two VFOs, putting the uplink into the upper (A) VFO, and the downlink into the lower (B) VFO. Uplink and downlink can be done from either VFO.
I used these VFO-specific settings with this radio, similar to what I have been using with the other HTs:
Uplink VFO:
SQL (005): 9 N/W (014): WIDE T-CDC? (019): 67.0 STEP ? (020): 2.50
Downlink VFO:
SQL (005): 0 N/W (014): NARROW STEP ? (020): 2.50
Another setting I had to enable for full-duplex operation was:
DUPLEX (031): ON
With the smaller tuning steps, I could get the AO-85 downlink lined up easily on my PX-UV973. It was about 5 minutes into the pass before I made my first QSO, with Glenn AA5PK in west Texas. A couple of minutes later, I made another quick QSO with Ed N7EC north of the Phoenix area. The receive audio while I transmitted was not really good - despite the satellite's elevation heading up to 56 degrees at the midpoint of the pass. The HT was able to operate full-duplex, but the other HTs I have tested with AO-85 have done much better. I could still hear myself through AO-85 a couple of minutes after these QSOs, until the trees in a neighbor's yard started to make it tougher to hear. The CW beacon from XW-2F was also starting to overlap with the AO-85 downlink, also.
Using my SDR receive setup (SDRplay receiver, HDSDR on an 8-inch Windows 10 tablet, AMSAT-UK VHF crossed dipole), my transmitted audio sounded OK. Not loud, but it was fine - similar to what I've heard from the other Chinese- made HTs I have tested. I have uploaded the audio recording I made from the HT, the RF recording from the SDR receive setup, and some photos, to my Dropbox space. You can get those files at http://dropbox.wd9ewk.net/ - look for the folder "20151127-AO85_Fox1A_XW2F-DM43". I also heard XW-2F near the end of the AO-85 pass, and I let HDSDR continue writing the RF recording to cover XW-2F until its LOS.
Since the PX-UV973 has been on the market for a couple of years, I did not have high expectations for it working AO-85 full-duplex. I was not surprised to see that it was a poor performer. If I had to rank this with the other 3 Chinese-made HTs I previously tested, this one would be at the bottom of the list by default:
1. Wouxun KG-UV9D 2. AnyTone TERMN-8R 3. Wouxun KG-UV8D 4. Puxing PX-UV973
Don't be drawn in by the low price of the PX-UV973. If you already have it, it can be used as one radio of a two-radio setup, probably as the uplink radio. Or use it for terrestrial repeaters, where it would probably serve that purpose adequately. I now understand why one dealer was hesitant to offer an opinion about this radio's performance for FM satellite work, when I asked about it early last year.
73!
Patrick WD9EWK/VA7EWK http://www.wd9ewk.net/ Twitter: @WD9EWK