[AMRadio] Screen Modulated 813


Geoff/W5OMR ars.w5omr at gmail.com
Mon Dec 11 11:23:17 EST 2006


Jack Schmidling wrote:
> Jim Wilhite wrote:
>> A bit of cherry red is ok.  Just remember what KYV said, don't exceed 
>> the plate dissipation of the tubes.
>
> Roger but isn't color a function of plate dissipation?
>
> In other words, can one use shades of red as real world indication 
> instead of relying on theoretical calculations?

in short, no.

some tubes 'color-up' at different levels than others.

K5SWK had a pair of 833's in his modulator.. one always showed more 
color than the other.

Seems I remember a time when there were a pair, and one did -not- show 
color at all, while the other one did.  He thought it wasn't working, 
but it was proven that it indeed was.

John/BXO has 4 813's in push-pull parallel in his modulator.. at normal 
voltage, there's one that always showed 'a little color' when at idle.

No, you can't depend on the color of the tube, to determine output of 
said tube.

--
73, etc



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