[Amps] 432 Cavity Amps; Thomson TH 331

[Carl]

The Chinese and Japanese often have clones of EU TV tubes.

Carl
KM1H


----- Original Message ----- 
From: "Patrick Barthelow" <apolloeme at live.com>
To: <amps at contesting.com>
Sent: Thursday, March 01, 2012 11:18 AM
Subject: [Amps] 432 Cavity Amps; Thomson TH 331


>
>
>
> Friends,
>
> After being offered for free, a Working Pull complete Tetrode cavity TV 
> amplifier on 470mhz,  (Sans power supplies which would have to be built) 
> and with possible plans to make a moonbounce Amp, I checked on 
> Pricing/Availability of spares, specifically the Thomson  TH 331 power 
> tube.  The Amp is capable of operation far above the legal limit; ~ 7.5KW, 
> so I wanted to know if it is easy to run at a  reduced  1500 watts out.
>
> Then I would be more comfortable with a Spare Tube around, and checked a 
> vendor to find that the   Large  Thomson TH 331 is no longer made, and the 
> vendor could find no equivelant tube, that was still made.  A surprise to 
> me also was the last price list with the tube, in 2006 showed a price of 
> $8700 list, ea.  Ouch.
>
> My question is,  It it possible to find a similar power tube to  with 
> matching Critical Anode, and other  dimensions that will swap into the 
> matching cavity system, and make cavity tuning changes to accommodate 
> different tube RF circuit  requirements?   Or... maybe impossible with new 
> replacement tube.  Perhaps a lot of TH 331s are out there used?
>
> If this is not practical to use/modify for Amateur radio Moonbounce use, 
> it is likely to be donated to a Large Dish installation for their use.   I 
> am guessing interplanetary radar use.  Is 7.5 KW output at 432, useful in, 
> say Moon Radar mapping studies?
>
> Here are photos of the tube, and Cavity cabinet:
> https://skydrive.live.com/?cid=2eb5c45df634a712#cid=2EB5C45DF634A712&id=2EB5C45DF634A712%21783
>
>
> 73,    Best Regards,       AA6EG,  Pat Barthelow
>
>
>
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