How would you interpret this waveform?
 

Repairing a BK E-200D rf signal generator. This waveform is what my
scope is showing on the output with the internal 400hz audio signal
applied at 50% modulation on an approx 500kHz signal. It should be a
clean sine wave. I am new to using a scope so not sure what the
waveform indicates, clipping? Power supply is not clean?
Here is a jpeg - thanks for any help!

http://mparkes.com/img_1807.jpg

Mike wrote:
Repairing a BK E-200D rf signal generator. This waveform is what my
scope is showing on the output with the internal 400hz audio signal
applied at 50% modulation on an approx 500kHz signal. It should be a
clean sine wave. I am new to using a scope so not sure what the
waveform indicates, clipping? Power supply is not clean?
Here is a jpeg - thanks for any help!

http://mparkes.com/img_1807.jpg

It looks like your modulating audio signal is a filtered square wave
(or a square wave run through an amp with inadequate bandwidth).

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On Mon, 21 Mar 2005 21:06:32 -0800, Mike
wrote:

Repairing a BK E-200D rf signal generator. This waveform is what my
scope is showing on the output with the internal 400hz audio signal
applied at 50% modulation on an approx 500kHz signal. It should be a
clean sine wave. I am new to using a scope so not sure what the
waveform indicates, clipping? Power supply is not clean?
Here is a jpeg - thanks for any help!

http://mparkes.com/img_1807.jpg

The first thing I would check would be the power supply at the
modulator and after. If that is solid I would then check the signal
at the input and output of the modulation stage.

This waveform appears to show that the modulating signal is overdriven
somewhere, so start at the modulator input and follow the signal
through until you see the problem.

Good luck.

John