[amsat-bb] HT for sats

Paul Stoetzer n8hm at arrl.net
Thu Jan 25 18:57:15 UTC 2018


The DJ-G7T does appear to be unsuitable for full duplex U/v operation.
In limited testing (only 3 passes - 2 with a whip, 1 with an Elk), I
experienced desense. I could still hear my own signal a bit, but it
was not clear. I even keyed up with a whip on 1.2 GHz during a pass of
AO-92 when it was in high speed mode and the 1.2 GHz signal mostly
wiped out the satellite reception.

Even just listening, the receiver performs poorly for satellite operation.

That said, I have used the DJ-G7T as my transmitter to make contacts
on three passes of AO-92 in mode L/v.


Paul, N8HM

On Thu, Jan 25, 2018 at 1:50 PM, Patrick STODDARD (WD9EWK/VA7EWK)
<amsat-bb at wd9ewk.net> wrote:
> John,
> "(O)n current HTs"? Other than some reports I have seen about
> the Alinco DJ-G7T and its poor receiver for FM satellites in
> general, it appears that the HTs that have been previously
> reported as capable of full-duplex operation with V/U FM
> satellites like AO-51 and SO-50 would be fine with the mode
> B (U/V) satellites like AO-91 and AO-92. With the uplink on
> 70cm, you avoid issues with harmonics which can be an issue
> on some radios capable of full-duplex operation when you
> transmit on 2m - keeping in mind that frequencies in the
> 435-438 MHz satellite subband can be very close to the third
> harmonic of the 2m uplink frequency.
> After AO-85's launch in October 2015, I tested a few Chinese-
> made 2m/70cm FM HTs that were advertised as being capable of
> full-duplex operation. None of them could work SO-50 full-
> duplex due to receiver desense, but could be used with AO-85.
> I wrote a series of AMSAT-BB posts about those tests at that
> time, and a link to a summary with other links to the specific
> models is in the AMSAT-BB archive:
> http://amsat.org/pipermail/amsat-bb/2015-December/056269.html
> I have been using the Wouxun KG-UV9D with AO-91 on a regular
> basis, either with my Elk log periodic or an MFJ-1717 2m/70cm
> long duckie. This radio, along with other HTs like my TH-D72
> and an old TH-D7 I had for a little bit, is capable of full-
> duplex operation with mode B (U/V) satellites. I have seen
> other reports online of hams using a Wouxun KG-UV8D (or one
> of its variants) to successfully work AO-91 full-duplex.
> 73!
> Patrick WD9EWK/VA7EWK
> http://www.wd9ewk.net/
> Twitter: @WD9EWK or http://twitter.com/WD9EWK
> On Thu, Jan 25, 2018 at 6:30 PM, John Geiger <af5cc2 at gmail.com> wrote:
>> Does desense on 2m occur with using Mode B FM satellites in full duplex on
>> other current HTs?
>> 73 John AF5CC

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