Drake tr4c problem
 

TJM wrote:
I have cleaned the original relay in several TR-4Cs without
success, Tom. Gary, K4OAH sent me the info on a fix.
You can get a plug-n-play replacement
that has gold contacts and works well for $17 plus
shipping from:

P&B R10-E1-Y4-V2.5K.

Hi Gang,

Yes, that's what's in there now... I knew it was fairly new.
Digikey carries them also for about $16.

Anyway went back in and started to get some pin voltages on the Vox
circuit tubes... stupid me got a small shock ( not use to these tube
rigs! ) and went to repull the relay.

Had prev cleaned them and this time found a sheet of wet/dry paper 1000
grit...

NOOOOOOOOO!!!! Don't do that! You will ruin the relay for life!

Bad! Bad!! Bad!!!

Seriously, the emory grit will embed in the soft relay contacts, and
will make a bunch of little nonconductive boulders that are certain to
mess the relay up.

The way to reform relay contacts is what I told you before. Take an old
hacksaw blade, and grind the flat sides on a course grinding wheel. (The
steel is too hard to have grit get embedded into it.) The fine scratch
lines that are left in the steel are perfect for burnishing the contacts.
If you don't have a grinder, a whetstone, or a diamond sharpening stone
will do just fine for scratching up the hacksaw blade burnisher. Take the
paint off of the blade first, though.

fiq I'd gently redo the contacts ( hell the relay is cheaper
than tubes! ).
While it was out I ran the relay by an outside power source... looked
like one or two of the contacts were mis-aligned...

That sounds like the real problem. Relays are made so cheaply these days
that alignment is seldom optimal.

-Chuck

Drake tr4c problem
 

While your suggestion is good for many boatanchor relays,
Chuck, this one has pretty tight contacts- I don't think
the blade would fit.
Hardly worth the effort, considering you can buy
one for a few bucks that has gold contacts and is
specifically designed for comm work.
73 Dave S.

Drake tr4c problem
 

David Stinson wrote:
While your suggestion is good for many boatanchor relays,
Chuck, this one has pretty tight contacts- I don't think
the blade would fit.
Hardly worth the effort, considering you can buy
one for a few bucks that has gold contacts and is
specifically designed for comm work.
73 Dave S.

Hi David,

I agree, it is best to replace, if a replacement is available.
When I use a hacksaw blade, I grind it to whatever thickness and
width I need. I typically grind to about 0.010 thick. (which takes
so little time on a bench grinder that you have to be careful)

In any case, the big point I was trying to make, is never, ever
use abrasive paper to clean up the contacts on anything. It will
cause the contacts to arc and burn from that point forward.

-Chuck

Drake tr4c problem
 

In any case, the big point I was trying to make, is never, ever
use abrasive paper to clean up the contacts on anything. It will
cause the contacts to arc and burn from that point forward.

Thanks Chuck /Dave...

But to be honest, I fiq it was worth it. The problem kept pointing back
to the relay! As a new relay (which I'm ordering) was only $16, I wanted
to eliminate the relay as a problem once and for all... as tubes were
much more costly.
And I did reclean them with alcohol after.

But maybe it was more of an alignment of the contacts in the end that
was also effecting it.

But the Drake is working fine, will swap out the relay soon and keep in
the spare pile along with several nos tubes.

Happy Holidays to all
Tom

Drake tr4c problem
 

Chuck Harris wrote:
David Stinson wrote:

While your suggestion is good for many boatanchor relays,
Chuck, this one has pretty tight contacts- I don't think
the blade would fit.
Hardly worth the effort, considering you can buy
one for a few bucks that has gold contacts and is
specifically designed for comm work.
73 Dave S.


Hi David,

I agree, it is best to replace, if a replacement is available.
When I use a hacksaw blade, I grind it to whatever thickness and
width I need. I typically grind to about 0.010 thick. (which takes
so little time on a bench grinder that you have to be careful)

In any case, the big point I was trying to make, is never, ever
use abrasive paper to clean up the contacts on anything. It will
cause the contacts to arc and burn from that point forward.

-Chuck

The good ole' style contact burnishers are still available. See:

http://www.hmcelectronics.com/cgi-bi...duct/6440-0002

You can Google up a search for contact burnishers and find many
examples. These are a MUST for old boat anchor equipment!

73, Roger

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Drake tr4c problem
 

Another thing I've run into in refurbing a bunch of TR-4s and
TR-4Cs is intermittants in the tube sockets.
The tube pins get oxidized and this causes no end of troubles.
Even in the final cage- I had one that kept acting weird until
I noticed that one of the finals no longer had a filament!
On some of the sockets- especially in the receiver front end
and the modulator- it took De-Ox-Id on the tube sockets
and tube pins to fix the problem.

Dave S.