[Collins] 51J parts

[Dr. Gerald N. Johnson]

On Wed, 2008-04-30 at 17:05 +0000, Bill Kirkland wrote:
> I've sent Ed the part.  The coil forms are tricky because they belong to a 
> sub-assembly
> which includes the tuning trim cap.  They are mounted as a package in the RF 
> section.

Thats kind of what I had expected.

> It would need to have identical characteristics as the other two coil forms 
> used in the
> RF deck for that band grouping so that they all track together as the 51J is 
> tuned
> either across the band or as the band switch is changed.

And L105, 108, and 112 have the same part number for exactly that
reason.
> 
> If folks are interested, I can remove an another sub-assembly and photograph 
> it.


It would be interesting but probably not worth the effort.
> 
> I didn't check the winding on L105 but I do know that the windings on some 
> of the
> coil forms connected to the IF tuning rack are not uniformly spaced wound.
> 
And that's almost as I expect, there's two choices for tracking, the cam
shape and a variable pitch coil. A good variable pitch coil makes the
cam linear and easier to create in a day before numerically controlled
machines. Just takes one hand made cam for the coil winding machine.

So without a coil to copy, we best keep our eyes out for parts supplying
radios to keep the good radios working.
-- 
73, Jerry, K0CQ, Technical Advisor to the CRA
All content copyright Dr. Gerald N. Johnson, electrical engineer