[BC] Outside source for checking Modulation Levels

[Ira Wilner]

Getting a stable  and clean 13587 sine-wave audio signal can be a bit
tricky.  I've used lower frequencies and just looked for the 3rd through 5th
Bessel null.  And, BTW the audio frequency isn't too critical even if it
drifts a smidge you'll be close enough.  I no longer own a continuously
variable audio generator, sigh!  But I do have a copy of the 1988 NAB
Broadcast and Audio System Test CD.  Bessel calibration tones are on tracks
37-44.

--Ira

 From: Cowboy

Back to the original question, before this whole Eric Small  muddying of the
water history, the short version is that yes,  you can clip a garden variety
O-scope to the un-deemphasized  audio output of an FM discriminator, then
modulate the transmitter  with an accurate 13586 hz tone.
 Increase audio level until the second carrier null is observed on