[AMRadio] Re: WRL Globe King 500C rebuild

Albert Santangelo ve3ajm at sympatico.ca
Fri Jul 7 02:05:55 EDT 2006

The power supply sounds FB...but the plate tuning capacitor on the Globe King is
just marginal when you run the stock modulator power supply. Any components which
have modulated B+ appearing on them would have to be upgraded...caps..the
bandswitch etc.


W5OMR/Geoff wrote:

> DLe9480907 at aol.com wrote:
> >Hello to all . well have gotten around to trying to restore my king that  was
> >salvaged from a basement flood. the PS and Modulator are gone but the RF
> >Deck is rehabbed and working great on caw with an out board globe vfo or xtal.
> >The question now is will my new 2000vdc @600ma power supply be ok to power the
> >modulator also? and was wondering about the modulator. I have a Stancor A3898
> > 300 watt vari match mod xformer and was wondering about Tubes I have a good
> >supply of 813 (Triode connected) or 572b. what do youall think
> >
> How much current is the GK500C drawing in the final, on CW?
> If I understand the nomenclature correctly, the '500' would/should be
> around 500w DC input to the final.  With 2000v, that would put the
> current around 250mA.
> I'd say you'll have plenty of current handling capacity at 600mA to
> handle the modulator.
> I'm not that familiar with the "C" version... what are the modulators,
> 811's?
> I found this old 'ad' on somewhere out there on the 'net...
> -----
> Globe King 500C:  transmitter; Ad:  JAN 58 QST; price $795.00
> wired; 540 watts AM, 540 watts CW, 540 watts SSB (with external
> exciter); 160 thru 10 meters; bandswitching.  RF Section: 6AG7
> crystal oscillator, 6146 buffer, 4-400A final, 12AU7 keyer, 6X5
> and 5Y3 low voltage rectifiers.  Modulator:  6SJ7 speech
> amplifier, 6AL5 compression rectifier, 6C5 amplifier, 6L6G
> driver, push-pull 811A modulators, 5Y3 low voltage rectifier,
> pair 816 high voltage rectifiers; Power Supply:  5U4G low
> voltage rectifier, pair 866A high voltage rectifiers, 0A2
> voltage regulator, 6AU6 VFO, 6CB6 VFO buffer; shipping weight
> 300 lbs.
> -----
> So, it's got a pair of 811A's.  I read also, somewhere, that the
> modulator deck had it's own power supply, that utilized a pair of 816
> mercury vapor rectifiers.
> Unless you've got a seperate Bias supply for the 811A's at 2kVDC, I'd
> say it's probably a bit much B+ to run on 811's.  1500v in Class B is
> about good, for zero bias.
> Yes, you'll have enough power supply with the 2kV @ 600mA, and the 811's
> will take the B+, as long as you put some bias voltage on the cathodes.
> An adjustable, well regulated bias supply between the 811A filament
> transformer center tap and ground would be a good place for that.
> --
> Driving your AM Rig without a scope,
> is like driving your car at night, without headlights. (K4KYV)
> --
> 73 = Best Regards,
> -Geoff/W5OMR
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