Just bought a Mackay Marine 3031a. Nice commercial-grade radio. Everything
works, but I have one question. The signal meter worked at first, but after
about 30 mins or so it became inoperable, resting at the far right of the
meter
glass. Has anyone experienced something like this? Is it an intermittant
problem with the meter? Any suggestions on how I could check this?

Reggie,

I'm not familiar with your particular radio, but most "S" meter circuits work
by monitoring the plate current of one or more tubes which are controlled by
the AGC line in the radio. As the signal strength increases, the AGC voltage
becomes more negative, biasing off the tubes and causing them to draw less
current.

From your symptoms, you could have one or more gassy tubes in the IF amp or RF
amp, or (more likely) a leaky coupling capacitor. Do you have a schematic? If
not, you should try to get one. I'd suggest measuring voltages around the
tube(s) where the S meter is connected.

Hint: The old wax/paper capacitors are the source of 98% of all old radio
problems. Sometimes it's best just to replace them all, then go from there.

Doug Moore KB9TMY (Formerly K6HWY)