On 11/03/2012 3:08 AM, klem kedidelhopper wrote:
So now I'm really confused. Are you supposed to start
off with 9.0 Volts at the battery terminals for voltage measurement
purposes or is it 7.50 Volts? I can say with every certainty that with
7.50V applied the actual circuit voltages did almost mimic what the
schematic shows when the radio was operational. Or has my supply been
at least 1.50V - 2.50V too low throughout this experiment? Lenny

The situation mostly doesn't arise. With a few (possibly only one)
exceptions, the annotated voltages are between two specified points, not
a voltage relative to ground. Indeed, most are between two points
neither of which is anywhere near ground.

The base and emitter voltages are relative to the positive supply rail.
Given the way that the biases are obtained, they wouldn't have been
sensitive to the supply voltage, which is no doubt intentional given
that the supply voltage from a battery will change as the battery is
consumed.

On another note, while replacing C38 has apparently cured the problem,
I'm totally mystified as to why. It would imply that C38 had failed such
that it intermittently behaved as if it had a resistance of many
kilo-ohms in parallel with it. It seems an unlikely failure mode for a
capacitor.

Sylvia.