" Uncle Peter" wrote in message
news:6JHPa.1933$zd4.313@lakeread02...
Some early commercial broadcast FM transmitters used very low
fundamental crystal frequencies; the large frequency mulitplication
was needed to produce the relatively wide FM deviation.

Pete


Good thought. So, I paged through an old FM book which has several
transmitter block diagrams. The RCA transmitter uses a master oscillator at
5.394 which is tripled a couple of times, then doubled, for an output at
97.1 mc. The same oscillator goes through divide by three, divide by four,
and another divide by four dividers. This ends up as 112.38 kc. But that's
not all. It goes through another divide by 5 divider. The crystal
oscillator, in this case 112.38 kc, similiarly gets divided by five, and is
applied to a couple of 45 degree phase shifters. Then both reference
sighals divided from the master oscillator and the phase shifted crystal
oscillator, are applied to a couple of balanced modulators which control a 2
phase motor coupled to the master oscillator's variable capacitor. Whew!

Maybe so. Thanks!

Frank Dresser