[amsat-bb] AO40 mode V/S2

["Wayne Estes W9AE" <w9ae@xxxxxxxxxxxxx>]

I just made a contact with Mike N1JEZ on mode V/S2.  Mike was easily
copyable on mode L/S, but only barely above my noise level on mode V/S.
Mike was running 150W to a 22-element CP VHF antenna, and that still put him
about 6 dB weaker than his L-band uplink.

I heard Mike make a QSO with W4MVB who was running 50W to a 22-element VHF
yagi, and was noticeably weaker.

After they were finished I gave Mike a call with 50W to a 14-element CP VHF
yagi.  My signal was even weaker still.  Mike could tell I was there, but I
had to give my call several times for him to get the full callsign.  I later
switched to CW, which Mike said was easy to copy.  He said my signal was
right at his noise floor using a G3RUH dish, G3RUH patch, and a DB6NT
preamp.  Mike's signal was not much above my noise floor using a G3RUH dish,
G3RUH patch, and a DEM preamp.

Later I heard Dave WB6LLO running 100W to 22 elements.  He was Q5 copy, but
still not much above the noise on my end.  My S-band receiving system is a
G3RUH dish, patch feed, DEM preamp, and TSI downconverter.

The bottom line is that the VHF uplink is "hard of hearing", but usable with
a lot of power and antenna gain.  It seems that 100W to a 22-element yagi is
the minimum for reliable communication, and that produces signals that are
MUCH weaker than the typical U or L-band uplink.  My 50W to a 14-element VHF
CP yagi was definitely marginal.

Wayne Estes W9AE
Mundelein, IL, USA




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