[Collins] What Is It?

[Dr. Gerald N. Johnson]

On Fri, 2007-06-01 at 00:04 -0400, Garey Barrell wrote:
> Jerry -
> 
> I meant to include the can size......   1.375 x 2 x 3.5.
> 
> The BFO can certainly seems likely, although I would have expected a 
> fixed BFO as late as 1970.  It's arranged so the variable cap shaft 
> could mate with a coupler for a front panel adjustment.
> 
> I just hate to tear it up if it was of use for it's original intent.
> 
> Thanks!
> 
> 73, Garey - K4OAH
> Glen Allen, VA
> 
That does shed more light. So its not BFO for S-line (all crystals) or
75A4 (PTO round can so it can turn with the main tuning for bandpass
tuning). So it would have to be earlier in the 75A receivers, maybe 51J.
What size is the variable? A small one like 15 or 20 pf might make it
the coil (which should be center tapped) for a crystal filter that would
extend the capacitor shaft to the front panel too.

That date says when it was made, not when it was designed and it might
have been made as a spare part because a customer demanded it then the
extras made were surplussed. I don't think anything made new in 1970
would have afforded that much volume for a coil/capacitor assembly. With
the push to transistors a whole radio fit in that volume.

I've checked a couple manuals, its not 75A3 or 51J. The 390 manual is
buried too deep to dig out handily.
-- 
73, Jerry, K0CQ, Technical Advisor to the CRA
All content copyright Dr. Gerald N. Johnson, electrical engineer