[Milsurplus] [Boatanchors] FMing Prog. Oscillators (was GE Portamobil)

[Glen Zook]

You can always phase modulate the signal.  Remember, most of the old tube-type "FM" units sold by Motorola, General Electric, etc., were actually phase modulated (PM) instead of being frequency modulated (FM).  Using PM would probably be easier to accomplish than other systems trying to FM the signal.
 Glen, K9STH 
Website: http://k9sth.net

      From: David Stinson <arc5 at ix.netcom.com>
 To: mrca at mailman.qth.net; boatanchors at mailman.qth.net; milsurplus at mailman.qth.net 
 Sent: Tuesday, February 26, 2019 8:15 AM
 Subject: [Boatanchors] FMing Prog. Oscillators (was GE Portamobil)
   
(Copied to other lists for general interest:)

I've been working on a concept.

Can't FM a programmable oscillator, but:
Say you have a rig that requires Fo/18 crystal.
So 146.52 would be 8140 KC.
And you have another crystal laying around, doesn't
matter the freq since we can order any freq prog. osc,
as long as the crystal's a fundamental.
Assume a common Color Burst crystal of 3.5795 Mc.

We order a 4560.5 KC oscillator.
With two transistors and a couple of diodes, 
we can sample mic audio through an adjustable
audio amplifier, then apply it to an oscillator
with the 3579.5 crystal, say in the Emitter lead.  
This crystal oscillator WILL FM at the audio rate.  
Output this and the prog. oscillator to a couple 
of diodes as a non-linear mixer. 
One of the products will 
be 8140 KC, FMing at the audio rate.
Don't need much of the mic audio since we'd
only need to swing the Color crystal about 300 
cycles, since it will be multiplied by 18.

   
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