In message .com,
G1LVN writes
I've got a couple:

1.Get a schematic and replace the components in bias circuit(s) of the
PA.
then
2. Get a service manual and retune the PA setting bias as indicated.

3. (you might get away with just 2.)

4. Then again it could be the ALC ;-)

(....5. or the drivers)

I have the service manual, but unfortunately don't have an audio signal
generator or scope any more, so cannot do much in the way of testing.

My current thinking is that either the PA (or driver) is dying, or that
the thermal conductivity between the PA and heatsink has degraded
(however, the PA does not seem to run any hotter than originally, and
the fan very rarely kicks in -- again, no more so than when it was new).



Aternatively send it off to Castle Electronics as they seem to know
what they are doing -

Good tip. I'll call them today.


they rarely quote input power in terms of Volts
DC for example.


I only quoted that to eliminate the PSU from the equation. A drop from
12v to 11.5 volts can make quite a difference to the output power.


--
Ian