From chrisc at chris.org  Mon Dec 22 14:25:50 2025
From: chrisc at chris.org (Chris Cox, N0UK)
Date: Mon, 22 Dec 2025 14:25:50 -0600
Subject: [10gigs] Interesting extract from a recent RaCom
Message-ID: <6512DF47-316A-4E7B-AEA3-D6988A781988@chris.org>

The following was taken from the "Data" page in October 2025 RSGB's RadCom magazine by G4JNT:

Q65 for 1OGHz
This seemed to happen quite suddenly. Afterthe Q65 mode had made such
inroads into microwave Moon bounce (EME), allowing many smaller stations
to take part, use of this very potent data mode just had to spread to terrestrial
paths. The situation is best summed up by a precis of comments made by
Dave, G4YTL on the microwave group chat:
"Together with others, l've been encouraging people to try data modes on
3cm tropo. / must stress that it's been tropo testing and not rain scatter or
aircraft scatter, which I am sure will require different modes. 0n 3cm tropo
I am currently running 2W to a 65cm dish. I am planning on getting up
to 10W and an 85cm dish. My first QSO was with Maarten, ON/PA0MHE,
(308kn) July 8th. We completed in as short a time as posslb/e with Q65-
60D. lt obviously didn't need 60s periods and, somewhat randomly, we
decided to try Q65-15C and completed as quickly as posslb/e.
?Over the next week or so others tried -15C successfu//y. But on tropo
the signal spreading is very slight and Charlie, DL3WDG, said to me that
therefore the narrower spacing of the -l5A submode should be OK and may
offer slightly better sensitivity, So subsequent/y I've been using -15A. 0n
July 12th I worked PA0BAT, for my best DX of 509km, using -60D. 0n July
18k I did some testing with Adrian, G4UVZ, to get him set up using Q65
for the first tine. We completed using -15C. The same day, I completed
with Nick, G0HIK (280km) using -60D and then with -15A. Then the same
day I completed with PE9GHZ (339km) using -15A. 0n July 27th, I worked
G0HIK again with -30C.
"The bottom line is that Q65 allows tropo communication under flat
conditions at drstances that can't be achieved with CW. Q65-6AD will dig out
weaker signals than the 30s or l5s peiods but often 15s is long enough. I
thinkthereforethatmy preferenceswould be (1)to use I0368. I85MHzas
the default frequency, as suggested by others, and (2) to use -15A as the
default; if that doesn't work, go to -30C or -60D by agreement. I personally
have no interest in confests so won't conment in that area. But the bottom
line remains: get more fixed stations active on 3cm outside UKAC.

Chris Cox, N0UK
chrisc at chris.org
https://www.credly.com/go/IR77aRbH2rFDdOiymuxu2w