[Amps] GS-35B; Best choice Int'l shipping?

Tue Apr 27 11:27:41 PDT 2010

RE GS 35 B Possible choice for Homebrew Amp:

Thanks Bill for your comment on the GS-35B  The efficiency may become important, if it means that you cannot get 1.5KW out of the GS 35B with 100 watts drive.  Whether the efficiency sucks more watts out of the wall socket/power supply  is less important than if we can get full output with a solid state 100 watt TX exciter.   

Some more questions about the GS35.  

Are all about the same reliability, independent of source?  what percentage random DOA?   Best purchase source?  USA dealers?  Eastern Europe hams?  New?  Used?  NOS?  I have seen suggestions for conditioning which recommended all newly acquired GS 35bs be operated at reduced B+ and heated for some time to Getter out any residual gas.

before applying full B+ for operations.

One of the first GS 35B Amps I looked at some years back used very simple clamps of the grid ring directly to the chassis, with a hole punched for access to the cathode/filiment power.   Almost no "Socket" per say.  And simple drilled holes around the base to allow cooling air to be chimnied. or ducted up through the anode cooler fins.

Also I recell a lot of backpressure, and flow reqts to the tube.  Is a GS 35B amp properly cooled, noisy, esp when compared to a typical 3-500Z pair which requires far less pressure to get the flow?

Also on a more practical level, I plan to ship various KW RF components, for this project,  to Uruguay, proabaly only the lighter ones...chokes, tubes, band switches, meters, etc.  What is the best  (Cheapest) choice for an international shipping company between USA and Uruguay?   

Thanks to those who have replied to earlier queries about sourcing the QRO power supply pieces.  I am hoping to find a sympathetic Radio Station engineer in Montevideo, or Salto,  that may source  a suitable, surplus to their use,  B+ transformer.

Thanks guys,

Best Regards,   
73, de Pat Barthelow AA6EG

> From: dezrat1242 at yahoo.com
> To: amps at contesting.com
> Date: Tue, 27 Apr 2010 09:20:46 -0700
> Subject: Re: [Amps] Helping a Uruguayan Ham build an Amp.
> 
> ORIGINAL MESSAGE:
> 
> On Sun, 25 Apr 2010 10:15:47 -0700, Patrick Barthelow
> <apolloeme at live.com> wrote:
Then even the possibility of choosing a GS 35B tube as as the basis of the amp. 
> 
> REPLY:
> 
> I would recommend against using a GS-35b. Their efficiency is low
> compared to other types. I and several others have obtained
> efficiencies in the range of about 50%, compared to about 60% for an
> 8877 and other comparable tubes. 
> 
> Aside from poor efficiency they do seem to work well so that is not
> necessarily a show-stopper, just something to consider. 
> 
> 73, Bill W6WRT 		 	   		  
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