[Milsurplus] PP-109 PSU Parts Needed

[WA5CAB at cs.com]

It might be interesting to determine what the failure mode was. If you hadn't 
said that it vibrates, I'd assume one of the contacts was welded. But that 
(rarely) plus sulfided (open) contacts are the only failure mode I've ever 
encountered. So I'd suggest looking for other problems in the supply, mainly 
shorted electrolytics.

Other mfg numbers for 3H6690-15 are as follows:

Mallory 1804S Shunt
CD 3334C Unknown
BACO VB006S01 Shunt
Unknown 571S Unknown
ATR 6427 Series

However, although they all carry the same Signal Corps Stock Number, not all 
will work in all PP-109's (or other supplies they were used in). 

There are two basic types of electro-mechanical vibrators, Series fed and 
Shunt fed. The Series fed have a contact electrically in series with the coil. 
The shunt type bring both ends of the coil directly out to pins on the base. The 
Series fed is hooked up the way the simple example diagrams always show, 
battery to coil to switching contact to battery common. The Shunt fed have the 
coil and one of the NO contacts connected to one end of the transformer primary. 
Battery, of course, goes to the primary center tap. 

I think that it was Mallory who pushed the Shunt fed type, claiming greater 
efficency. I suspect that the power savings were minimal, but in any case, 
50-60 years on, it is much more difficult to clear the tungsten sulfide layer off 
of the contacts in the Shunt fed types than in the Series fed ones.

Anyway, back to my statement. The PP-109, PP-112 as well as the three small 
supplies and the DY-88 and DY-105 are originally wired to run with either shunt 
or series type vibrators. And the Signal Corps Stock Numbers don't define 
which is in the box. But in the 60's there was for unknown reasons an MWO on at 
least the PP-109 and 112 that removed the wiring for the Series fed vibrators. 
So supplies thus modified will only work with the Shunt fed units.

The PP-109 that started this thread, as it has ATR 6427's, must not have been 
modified, so it should work OK with any of the ones on the list.

The fuse type used is the GRC sets is the AGU or F07A, rated 32 volts. I have 
also seen some of the same physical size made by Bussman with paper wrapped 
around the body that say they are rated 250 volts, but no type number.


In a message dated 1/12/2007 7:23:21 PM Central Standard Time, 
wdonzelli at gmail.com writes: 
> >ATR
> >VIBRATOR
> >TYPE 6427
> >6 VOLTS
> >ST. PAUL MINNESOTA
> >MADE IN U.S.A.
> >3H6690-15
> >
> >Last # is the Sig. Corps stock #.
> >I am tempted to pry open the can and pop the contacts apart. Is this worth 
> the time?
> >Anyone know of an equivalent chart? Fair has several listed, but I don't 
> know what to order, if anything.
> 

Robert & Susan Downs - Houston
<http://www.wa5cab.com> (Web Store)
MVPA 9480
<wa5cab at cs.com> (Primary email)
<wa5cab at houston.rr.com> (Backup email)
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://mailman.qth.net/pipermail/milsurplus/attachments/20070112/5c76331c/attachment.htm