[Meteor-Scatter] Using WSJT/FSK441, advice please

[Stephen Ayling]

Hello Everyone,
About 2 weeks ago I began to use WSJT in FSK441 mode for meteor scatter on 2
metres, fortunately it seems, also coinciding with a period of good
reflections, and I completed qsos easily with several stations at good
distances. As a result of this initial flush of success I thought all was
working satisfactorily, despite my setup being rather on the minimalistic
side for m-s working.
Subsequently conditions seemed slowly to deteriorate, infrequent pings which
were short and weak, and I was able to decode only nonsense from them, even
though my settings in WSJT should have resulted in at least some fairly
reliable decodes. This situation continued every day, and I began to realise
that all was not OK. Even though I changed to another computer with
different OS, processor and RAM, nothing improved; pings, though  above
noise, decoded gibberish.
Then I analysed the captured .wav files from the first successful qsos,
pings were generally 10dB plus above noise, and duration several hundreds of
milliseconds; so why was I not decoding properly pings approximately in the
range, say  2-8dB and 20-100mS long, even though, as I have already said,
program settings, W, S, DF, Tol, etc suggested I should be able to ?
Somewhere in my setup there must be a lack of sensitivity. Pings either
strong or long decoding OK; but pings either weak or short not doing so.
My 2 metre transceiver is the Yaesu FT290R. On this rig the agc is fixed.
There is no agc switch and no possibility to select different agc
time-constants, or indeed switch it OFF. Is this the problem ?
I would welcome any comments and advice on the correct use of agc,
particularly from anyone who uses the FT290R with WSJT/FSK441.

My vy 73 de Steve, SO5AS, ( KO02jd ).