[Milsurplus] ARC-4 questions

[Hue Miller]

Someone over at the GB ( "Glowbugs": vacuum tube construction & radios ) has a dozen
crystals i think are ARC-4:

"> >I have a dozen Western Electric crystals. They are marked 703A
> Crystal
> >Unit. Some are 142.020 MC, some are 140.580 MC and some are 142.560
> MC.
> >They are three pin units.  The package is approximately 1 3/16 wide
> X ¾
> >deep X 1 3/16 tall (not including pin length). Some have orange USN
> stamps
> >(the one with the anchor). Anyone know what they are for? Anybody
> need
> >them? Anybody know their fundamentals (or the multiplier or formula
> used
> >to arrive at their stated frequencies)?
> >[]
> >
> >
> >73,
> >Chris
> >W7JPG "

I looked up the schematic in the "Surplus Schematics Handbook 1960". A couple
questions: what are the multiplication schemes for receive and transmit? How did
they get a guard channel, when i only see 4 R&T crystals?

The person having the crystals wants to dispose of them. Cheap or free, i think.
Not much use as no hambands, but???  -Hue Miller