[Collins] Fw: Trim Ring Needed and relay needed

[Dr. Gerald N. Johnson, electrical engineer]

Its not been used by Collins, but I prefer to use the P&B KHP17D11-110
VDC relay and its associated socket. There are numerous crosses, in W.W.
Grainger I find KHUA-17D11-110. In NTE it should be an R12-17D3-110,
however many distributors don't carry it because they don't think
there's a use for 110 volt DC relay today. The Tyco 156-14F200 with 110
volt DC coil looks right. The KHAU is in the latest Allied catalog for
$8.90. The solder in socket, 27E006 is $1.59.

The original relay is a short form telephone type with a built up
contact stack that has a very small contact motion, very little gap when
open and is easily damaged by working around it or by bending the solder
terminals for access. They require very skilled contact adjustment after
assembly. My boss, Lloyd Winter told me that they had a major problem in
the factory over those relays. They came from the maker wrapped in
tissue paper and individually boxed. To save shelf space at one point
the warehouse unboxed and unwrapped them and tossed them into bins. Few
worked after assembly. They had to teach the warehouse people that they
were delicate. And they still had to do some contact adjustment after
wiring.

The relay I prefer is an armature type relay (and I know relays of that
style were in the Collins parts because I used them, I don't think I put
them there) that has greater contact motion, better contact wipe, and no
need for contact adjustment. There is a possibility the armature type
relay will make a little more noise from the clapper striking the pole
piece. The trade off is far better relay life. And by using the socket,
super ease in replacement.

The plug-in relay Collins used in later radios is still a short form
telephone type with most of its disadvantages saved only by being in a
plastic case to protect those delicate contact adjustment.

I KNOW these relays work in the 32S because my dad did it to his 32S1 15
or 20 years ago.

73, Jerry, K0CQ, Technical Advisor to the CRA
-- 
Entire content copyright Dr. Gerald N. Johnson, electrical engineer.
Reproduction by permission only.