[Milsurplus] GRR-5 Parts needed

[WA5CAB at cs.com]

Fibber & Al,

Sometimes it can take up to 12 hours to break through the sulfide layer.  
Also, for 6 volt and under vibrators, I recommend a 25 watt light bulb.  For 12 
or 24 volt ones, a 12 watt is sufficient. 

And although the two vibrators used in the PP-308 only came in Series Drive, 
some WW-II and some Korean War vintage sets used Shunt Drive vibrators (or 
both types interchangably).  Clearing the contacts in these is a little more 
complicated.

And finally, in the general case it isn't only the contact set that controls 
the coil that you must clear.  Once you get the thing vibrating, you have to 
go on and clear the rest of the contacts as well.  To do a 3H6691-15 (the 
vibrator in question) requires three light bulbs (the 2nd and 3rd can be 12 watt), 
or at least two if you do the NC and NO contacts one at a time.

In a message dated 7/20/2006 7:57:07 PM Central Daylight Time, al at ar88.net 
writes: 
> Fibber,
> 
> It's usually possible to "wake up" an old vibrator.  Clip-lead the coil, 
> normally-closed input contacts, and a 60-watt light bulb in series, and 
> apply 117 VAC for 30 seconds or so.  Apparently, sulfur, used to 
> vulcanize the foam rubber found inside, oxidizes the contacts.  High 
> voltage breaks through the coating and allows them to burn clean in 
> short order.  Even NOS vibrators suffer this malady.  I'm about 9 for 9 
> with this procedure.
> 
> 

Robert Downs - Houston
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