[Milsurplus] What's With 2,000 Volt, 50-Watt Xmtrs??

[John J Mccarty]

Ray and all;

   Just a data point.

    When I first fired up my GP-7, the 803 was "gassy". Glowed a very pretty
blue and drew way too much plate current. I don't think the GP-7 was ever used
before I powered it on but really can't swear to it or if the tube was original
to that rig.


73


n9hrt

On 11/17/2010 1:12 PM, Ray Fantini wrote:
> State of the art nineteen thirties design was excessive plate voltage and low plate current, by today's standards at least. Way easier to obtain equal power with low current at high voltage than medium voltage at medium current with old style filter capacitors and rectifier tubes. The 803 is a great tube, think I brought it up before that I have used one in a TBW and heaped great abuse on it without being able to harm it and ask at that time on the reflector and appears no one has seen one fail other than thru sheer stupidity like excessive filament or braking the envelope.
> Ray Fantini KA3EKH
> 
> -----Original Message-----
> From: milsurplus-bounces at mailman.qth.net [mailto:milsurplus-bounces at mailman.qth.net] On Behalf Of mac
> Sent: Wednesday, November 17, 2010 1:00 PM
> To: David Stinson
> Cc: arc5 at mailman.qth.net; milsurplus at mailman.qth.net
> Subject: Re: [Milsurplus] What's With 2,000 Volt, 50-Watt Xmtrs??
> 
> Fifty watts out with 2KV on the plate is the (suppressor) grid  
> modulated specification for the 803.  The tube is good for 200 watts  
> out on CW with the same plate supply.  Designers choice, maybe, in the  
> case of the AVT-12 to save the weight of a modulation transformer and  
> extra circuitry of a plate modulated rig designed around lower  
> voltages. Same route taken in the TBW for ex.  Pair of 803s in the TBL  
> good for 100W phone and 400W+ on CW as Howard mentioned.  Same deal in  
> the TCK with a pair of (control) grid modulated 813s in the PA..
> 
> Dennis D. W7QHO
> Glendale, CA
> 
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