17-12-2023, 10:57 PM
You don't really need modulation on a sig gen to test an FM tuner.
There should be a cap about 4uF 40V or 50V with + to chassis on the FM detector. The voltage on it will vary with signal level. They often dry out. A 4.7 uF should be OK. A 35V or 40V rating should be OK, certainly you get at least -25V there with a good signal and zero with no signal.
Check audio level from an off air station at output.
A scope may detune the IF!
Is there an amp & speaker with volume control? Or is it just a separate tuner only?
There should be a cap about 4uF 40V or 50V with + to chassis on the FM detector. The voltage on it will vary with signal level. They often dry out. A 4.7 uF should be OK. A 35V or 40V rating should be OK, certainly you get at least -25V there with a good signal and zero with no signal.
Check audio level from an off air station at output.
A scope may detune the IF!
Is there an amp & speaker with volume control? Or is it just a separate tuner only?
