[Boatanchors] Need Globe King 500C Modulator Question

[Dennis DuVall]

Hmmm…  Sounds like Globe/WRL was having trouble with blown mod transformers.   A lot of  iron here and care must be taken when initiating and especially when interrupting current 
flow through the transformer windings, otherwise destructive voltage transients (spikes) can occur.  Took a look at the 500C schematic and not obvious the designers included ANY 
snubbing or other protective provisions on or around the modulation transformer. The somewhat huskier Military T-368 has spark gaps spaced  at 0.0625 inch on both the mod xformer and 
the HV filter choke.  Might be a place to start.

Takes me back  60 years to when I was in college.  A ham friend of mine in the same class was a well off “townie” and he was the very proud owner of the first version of the 
Globe King, the one with a pair of V-70-Ds in the PA.  His sad story was that the modulator blew up the first time he ever tried to operate the thing on phone and he 
would only run the radio on  CW after that.  Anyone else have history to relate?

Dennis D.  W7QHO
Glendale, CA

*******************


> On Nov 29, 2015, at 1:46 PM, Gary H. Harmon, Jr. <gharmon at idworld.net> wrote:
> 
> From my friend Ron......
> 
> 
> 
> I had an epiphany on the control circuitry of the GK "B" modulator and now
> know how to do it.  Took a while, brain fog!  All I need to figure out is
> how WRL made the spark gap device across the secondary of the modulation
> transformer on the "C" modulator and also the value and wattage of the load
> resistor they installed across the secondary.  Have you ever seen this
> device and resistor?  No pictures in the manual and no references in the
> parts list for either.  It just shows up in the "C" schematic.  
> 
> 
> 
> Anyone know the answers?
> 
> 
> 
> Thanks and 73,
> 
> 
> 
> Gary H. Harmon, Jr. - K5JWK - HAM Radio and ATARI Archaeologist
> 
> 6003 Archwood
> 
> San Antonio, TX 78239-1504
> 
> 210.657.1549h / 210.884.6926c/t
> 
> gharmon at idworld.net
> 
> 
> 
> "Too many projects - Not enough time!"
> 
> "Retirement = Every day is a Saturday except Sunday"
> 
> http://www.grissomroadcoc.org
> 
> 
> 
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