On Tue, 2007-08-07 at 13:48 -0400, Louis A. Ciotti Jr. wrote:
> I would do this, but I do not have any source for injecting the signals
> Right now I only have an old 40 MHz oscilloscope and a DVM...
Have you a finger? it can inject signals while acting as an antenna. For
the price of a battery and an op amp you could have a decent audio
source. Have you another receiver you could tap for signals? Even a
transistor radio will provide audio and harmonics from its local
oscillator that can be radiated into the radio under test.
A 40 MHz scope makes a pretty decent signal tracer if you can inject a
signal, say from the crystal calibrator, so it may be that you need to
fix the calibrator first, then trace signal from the front end in just
the opposite direction you would trouble shoot with an injected signal.
Even a Heathkit SG-8 does a decent job of signal injecting.
Check each stage for DC voltages, particularly bias voltages on gates
and bases. When those match emitter/source and collector/drain voltages,
the suspicion that the device is melted is high, very high.
73, Jerry, K0CQ
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