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Setup to See S-Curve in FM Demodulator

Nov 7th 2020, 17:18

Switch626

Joined: Mar 18th 2016, 05:04
Total Topics: 0
Total Posts: 0
Hello all,
I was doing an alignment in a FM radio, your standard 88MHz-108MHz receiver. I completed the alignment but then thought I would see what a S-Curve looked like. I am injecting the FM signal into the base of a transistor (have a capacitor in series) that feeds a ratio detector tuned to the 10.7MHZ IF. I know I need two frequencies to view the curve in XY mode. Anyone know what the signals are:
Do I modulate the 10.7MHz IF or sweep it?
Where does the second signal go for XY?
Any reference or help would be appreciated.
73's
AG5EV
Nov 7th 2020, 20:54

WA0CBW

Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0
Are you using a sweep RF generator?
Bill
Nov 7th 2020, 21:34

Switch626

Joined: Mar 18th 2016, 05:04
Total Topics: 0
Total Posts: 0
Hi Bill, Yes, I am using a sweep gen,

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