[ARC5] On Hacking - 100 watt ARC-5s

[Kenneth G. Gordon]

On 16 Oct 2012 at 14:15, Mike Hanz wrote:

> Those are valid points, John, _*/if/*_ the set was operated within its
> standard voltage and current design envelope.

Yes.

>  Unfortunately, some
> hams wanted a lot more power out of them, using plate voltages that
> exceeded the published 600v maximum by significant margins.

750 to 800 was not unheard of. I remember 750 VDC being quite common 
and easily achieved with TV power transformers.

> a 50 ohm resistive antenna load.  He claimed he was getting close to
> 100 watts out of those little boxes.

Well, a pair of 807s will INput 120 watts: 1625s are simply 12 V 807s. Why 
not? Plate dissipation ratings of an 807 were significantly higher than the first 
6146s in fact...and 1625s were MILITARY tubes, and therefore, tougher.

>  I'm not sure how he was cooling
> them...

Leave the cover off.

>he must have used a blower hung on the side of the tube
> compartment.  I don't see how he could have obtained any appreciable
> life out of the tubes

Didn't...we figured that as long as the plates didn't stay red for very long, it 
was OK.

> at that level without forced cooling.  But then
> again, 1625s were, what...a quarter apiece?

I remember them as $0.15 each...and I couldn't afford them then...

Ken W7EKB