[Hammarlund] question

[rbethman]

  "uckumpucky" is a coal tar based material used throughout the '40s, 
'50s, and '60s in potting transformers and capacitors in accordance with 
the Military Specifications inn force at the time.

The R-390s and R-390As had their capacitors done this way.  The BC-610s 
went this way shortly after their introduction into the Military 
versions.  Beyond the "D" and "E" models, this became the method used on 
chokes and transformers.  Look at any of the "late" models, eg., 
BC-610H, BC-610I, and the T-213.  They are all potted components.

This remains hard during normal use and temperatures.  Should the device 
fail, the temperature exceeds the range of it being solid.

It IS a royal PITA to get out of the canned capacitors.  Most that have 
gone to re-stuffing them have had to apply heat, and scrape the inside 
of the can to get rid of it.  They then replace the internal capacitor 
sections with modern electrolytics.  Most, if not all, use Teflon 
"spaghetti" tubing to cover the hot leads.  (I know that I do.)

In the instance of the 2uf oil filled cap on the R-390A IF module, I 
have left it in place - BUT put a modern polyester film capacitor in the 
circuit, while disconnecting the original

During the "late" '60s and into the the '70s this changed to a true 
resin based compound.  This also was followed by a dense foam material, 
and finally capped off by coating circuit boards with clear resin on 
bothe sides of the boards.

A perfect example of this treatment is/was the JSIDS, (Joint Services 
Intrusion Detection System.).  A high tech solution to an alarm system.  
Personally - I'd love a JSIDS in my house in lieu of the "junk" that the 
majority of "Security Companies" install!  All wiring is INSIDE EMT, or 
thin wall conduit.

Bob - N0DGN

On 7/28/2010 1:54 PM, Roy Morgan wrote:
> On Jul 26, 2010, at 5:19 PM, RICHARD MC KINNEY wrote:
>
>> What's an uckumpucky????
> Not "an" but a material or substance.
>
> The term's true origin may be lost in the annals of the R390 mailing
> list.  It was used there first many years ago, as I remember, to
> describe the gooey gunk inside the plug-in electrolytic capacitors
> found on the audio module of the R-390A radios.
>
> Roy
>
> Roy Morgan
> k1lky at earthlink.net
> K1LKY Since 1958 - Keep 'em Glowing!
>
>
>
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