Hi!
After testing a few different HTs over the past week using some common settings, I went back to an HT I tried the first weekend we had AO-85 in orbit and gave it a try with those settings. The Wouxun KG-UV8D, which had been on the market since early 2014, was a radio that I thought showed some promise for full-duplex operation with U/V FM satellites. I tried it with the Fox-1A engineering model at the 2014 ARRL Centennial Convention and 2014 AMSAT Symposium. With some adjustments in how I used the HT, trying to simulate working a satellite in orbit, I was convinced last year that this radio would be an option for full-duplex operations with the Fox-1 series of U/V FM satellites. I held onto the KG-UV8D to try it with a U/V FM satellite, whichever one was launched and operational first.
Simple question - can the KG-UV8D work AO-85 full-duplex? This was already answered last month, but I'll answer it again here in a word...
Yes.
This radio is slightly larger than the KG-UV9D I previously wrote about, a fatter HT when held. It has a menu system like most of the Chinese-made HTs, including the KG-UV9D which has replaced the KG-UV8D on the market. There are differences in the menus between the KG-UV8D and KG-UV9D, but I was able to use the same key settings in each VFO of the KG-UV8D:
Uplink VFO:
STEP (01): 2.5 SQL (02): 9 WN (08): WIDE T-CTC (16): 67.0
Downlink VFO:
STEP (01): 2.5 SQL (02): 0 WN (08): NARROW
It doesn't matter how each VFO is used. I prefer the upper VFO for the uplink frequency, but that is not mandatory. I plugged an audio splitter into the speaker jack, feeding audio to my Sony audio recorder and an earpiece. Using an earpiece or some sort of earphones is recommended when using a radio for full-duplex operation, to prevent receive audio from feeding back into your microphone. With HTs like the KG-UV8D using receive filtering that is sharper than what is typical in the Icom/Kenwood/Yaesu HTs, I find that using the smaller tuning steps and making adjustments on both uplink and downlink frequencies is recommended.
I worked an AO-85 pass Saturday (28 November) afternoon at 2252-2306 UTC, a 67-degree pass to my west. During that 14-minute pass, half of it (just over 7 minutes) saw the satellite at or over 20 degrees elevation, which I found last month as my "magic number" when trying to work AO-85 with less transmit power - like we have with HTs. What was interesting about this pass is that I could quickly change the downlink signal from good copy to poor with a slight twist of my antenna. When I first tried transmitting to AO-85, and if I wasn't lined up with the downlink, I would hear some additional noise and - at some points - it sounded like mixing that yielded the local National Weather Service radio station in my ear. Around the midpoint of the pass, the mixing was not present, but I could tell that the downlink would quickly degrade if I didn't have the antenna lined up with the downlink. I started with 145.980 MHz as my downlink frequency, and during the pass tuned down to 145.9875 and then 145.975 MHz for the last part of the pass. These adjustments were the only times I needed to switch VFOs during the pass.
Not many were on the pass, and I was able to work everyone I heard on the pass. John K8YSE/7 was on as the satellite came up from my northwest, and he was joined by a few others - Wyatt AC0RA in Iowa, Frank K4FEG in Tennessee, Ed N7EC north of Phoenix, and Ron N8RO in Texas. As I was using the KG-UV8D and Elk to work these stations, my SDRplay SDR receiver with an 8-inch Windows 10 tablet and HDSDR connected to my AMSAT-UK VHF crossed dipole was making an RF recording of the AO-85 downlink. The RF recording, along with the MP3 audio I recorded from the HT and other files, have been uploaded to my Dropbox space at http://dropbox.wd9ewk.net/ (look for the folder "20151129-AO85_Fox1A-DM43" and the recordings with names having the time around 2250 UTC).
Even after this test of using the KG-UV8D to work AO-85, I won't change my ranking of the Chinese-made HTs I have tried with this satellite:
1. Wouxun KG-UV9D 2. AnyTone TERMN-8R 3. Wouxun KG-UV8D 4. Puxing PX-UV973
Wouxun learned from the issues with the receiver in the KG-UV8D, leading to the improvements I saw using the KG-UV9D on comparable AO-85 passes. If the receiver didn't have the extra noise and mixing taking place when the AO-85 downlink wasn't strong, this could have been tied with the AnyTone TERMN-8R for second on my list. The issues I heard with the KG-UV8D receiver, on the other hand, are not as bad as what I heard from the Puxing PX-UV973 - a small benefit, but still (in my opinion) a reason to rate the KG-UV8D above the PX-UV973.
When I saw that the KG-UV8D was able to work AO-85 full-duplex last month, that vindicated my comments last year after testing it against the Fox-1A engineering model. At the same time disproved some comments I saw on the QRZ.com satellite forum from 18 months ago like:
"... the '8D - like the Puxing UV973 - although are true dual-receive units, that they are not suitable for U/V nor V/U sat ops ... Considering Alinco couldn't accomplish that with a $250 HT, I wasn't really surprised that these $100 units couldn't do it."
I have seen similar comments to the above in other forums, and in reference to other dual-band HTs that I have recently tested against AO-85.
This ignores the fact that before AO-85, the last time we had a U/V FM satellite (excluding the ISS U/V cross-band voice repeater) was SO-35, which went silent in 2001. Unless you went rogue and used an HT on a U/V transponder, there wasn't a satellite that could be used for a true real- world test of this HT like I have done with AO-85. As for the reference to the DJ-G7T, that radio arrived on the ham market in 2009, 5 years before the KG-UV8D, and what Alinco was (or wasn't) able to do with the DJ-G7T really isn't relevant to what Wouxun did with the KG-UV8D. Even though none of the Chinese-made HTs I tested are able to work V/U FM satellites like SO-50 and LilacSat-2 full-duplex due to receiver desense, Wouxun certainly learned lessons and improved the receiver from the KG-UV8D to the KG-UV9D.
After these tests, I have used 5 different HTs and an Icom IC-2820H 2m/70cm FM mobile radio to make QSOs via AO-85 in the past 7 weeks. It has been fun to try these radios out with similar settings. Having this knowledge helps to answer questions I get via e-mail, in online forums, and at events where I represent AMSAT (i.e., hamfests). After the initial disappointment that HTs would not be able to work this satellite from AOS to LOS, I think it should be clear that HTs are a viable option for working AO-85 during portions of higher passes. Working a U/V FM satellite is different than the V/U FM satellites most have been familiar with, but there are now a few options for using a single handheld radio to work AO-85 full-duplex - and a two-radio setup remains a viable option for full-duplex operation.
73!
Patrick WD9EWK/VA7EWK http://www.wd9ewk.net/ Twitter: @WD9EWK