hhhmmm, could it be a dirty (or bad) relay? I have a Yaesu FT-102
(vintage around 1984 or so) It had trouble with one of the relays till it
were replaced.
It had the same symptoms as you describe.
Give Yaesu a call and ask for a tech.
Good luck.
73 , Mark

M Wilson wrote:

Hi,

I have an FT-1000MP, the original, not Mk-V, not field, vintage is
1999. Recently I have noticed that if I turn the radio on 75 meters,
the receive is low.... until I just tap the mike or key, then the
signals jump up 10-20db, stay there for a while, and eventually, after
4-6 minutes, fade down, until another mike tap is applied. This will
continue all night. Antenna is a resonant dipole. It seems to happen
only on 75/80... preamp problem? should I switch to flat?
Suggestions?

Thanks!