[ARC5] Re-furbishing BC band receivers...

[Kenneth G. Gordon]

I've been going, slowly, through my stash of parts, trying to identify to 
which receiver each should belong, separating them into individual 
storage "thingys" and labeling them.

Today, I found several boxes of parts which I had forgotten about. In one 
of the boxes were four coil-boxes for BC band receivers, and 19 ea 239 kc 
IF cans.

Trouble is, 16 of those were for the 2nd IF only, 7269, one loose single 
was for the 3rd IF, 7270, in a BC-946, and there was exactly one complete 
set of IF cans for either the BC-946 or an R-24/ARC-5.

I also found 10 each (what look like new) 239 kc BFO cans that I had 
bought from Fair Radio Sales some time ago.

I also found three complete BC band receivers, 2 ea BC-946s with added 
power supplies, and one ARA, relatively unmolested, and at least 4 
"hulks", 2 of which could probably be "refurbished" enough to look and 
work "acceptably". The other two were simply hacked to ribbons.

And I have one R-22/ARC-12, BC band receiver, which, without too much 
effort, could be made to work and look acceptably.

Does anyone have any clear idea of the real difference between the IF 
cans? 

The ARC numbers on the cans would be 7268 1st IF, 7269 2nd IF, and 7270 
3rd IF in the BC-946 and in some R-24s. Other R-24s use a 7268 1st, 9635 
2nd, and 9634 3rd IF transformer....at least according to the three 
manuals I have so far examined.

>From what I can so far see from the drawings in the AN/ARC-5 manual, AN 
16-30ARC5-2 on pages 277/278, the 2nd and 3rd IF transformers appear to 
be identical internally, the only difference being the base plate. Both 
have both primary and secondary tapped, and both appear to be wired 
identically.

The first IF transformer (7268), however, is not tapped at either the 
primary or the secondary. But other than the orientation of the 
baseplate, it is otherwise identical internally and is wired identically 
to the 2nd and 3rd IF transformers.

Suggestions?

BTW, the AN/ARC-5 manual I have (in PDF) contains very noticeable errors 
and missing information.

Ken W7EKB