[Milsurplus] 1944 AAF Hand-Out for SCR-522

[Jack Antonio]

On 11/17/2018 6:46 PM, Hubert Miller wrote:

> But, what I am puzzled by, is 11, 13, 17th harmonics are from prime numbers. If you try to generate power from say the 13th harmonic
> in one step, you end up with very small power. Enough for a heterodyne frequency meter, but not enough to drive an RF power am5p.

The receiver uses different harmonics for different frequency ranges.

100-108   11th harmonic
108-116   12th harmonic
116-124   13th
124-132   14th
132-140   15th
140-148   16th
148-156   17th
156       18th

The end result of doing it this way is that in all cases, the crystal
frequency lies between 8000kc and about 8800 kc.

The crystal oscillator is fed to a two stage amplifier, I think both
stages are tuned to the mixer injection frequency, but would have to
more research into that.

I don't know exactly *why* they designed it this way, I have a hunch,
but the only hard piece of information I have is that with a 12 Mc IF,
they needed to avoid using crystals near 6000kc, the second harmonic
would fall into the passband of the IF.

Jack Antonio
WA7DIA