I am trying to fix my recently and suddenly deaf SX-190 receiver and
can't seem to find the problem. I have a DMM, an uncalibrated sig
gen, and a 100 MHz scope available. Of course, I have schematics,
etc.

The radio is almost completely deaf on all bands, with no indications
on the s-meter. I can hear the calibrator on all bands at a very low
level. I have verified that the HFO, VFO, power supply, and audio amp
are all working. I have injected a very small signal into the antenna
input and can see amplitude increasing at each stage through the 1st
455 kHz IF amp. I see 6Vpp at the collector of Q13. Looking at the
collector of the next stage(Q14) the signal is down about 30 dB.
Between the two stages, there is a mechanical (ceramic?) filter and a
transformer. DC bias on the stage looks fine.

It looks as though either the transformer or mechanical filter have
croaked, but I can't be sure. Any suggestions for how to test a
mechanical filter? Do those things die?

Incidently, I have checked the solder connections and they look OK.

Thanks,

MR