[Amps] 144 MHz GS35B update

[Carl]

That means nothing if the input and output were not retuned at each step or 
modified as needed. What class and bias is being used at each step and are 
the tube curves being used to select the sweet spots?

The GS-35B is also known to like high drive BUT Ive yet to see what that 
does to IMD. Hams are known to want more more more RF but care little about 
the consequenses

A GG amp has poor input-output isolation so one circuit affects the other 
and becomes more noticable as the frequency increases. This is also the 
primary reason why builders often have to make changes from a published 
circuit, especially at VHF and above.

Carl




----- Original Message ----- 
From: "Peter Voelpel" <dj7ww at t-online.de>
To: "'Amps'" <Amps at contesting.com>
Sent: Tuesday, May 02, 2017 6:50 AM
Subject: Re: [Amps] 144 MHz GS35B update


> Efficiency seems to be better with lower voltage but more drive.
>
> http://www.qsl.net/dl4mea/2GS35B_de_en.pdf
>
> In that example of a W6PO design efficiency is:
>
> 43% with 20W drive at 2,8KV, output 450W
> 70% with 100W drive at 2.45KV, output 1200W
>
> 20% with 20W drive at 4.4KV, output 400W
> 59% with 100W drive at 4.3KV, output 1900W
>
> 69% with 150W drive at 2.4KV, output 1500W
> 64% with 200W drive at 4.2KV, output 3250W
>
> The amplifier is very well documented in English and German language.
> File size is 4.4MB.
>
> 73
> Peter, DJ7WW
>
> -----Original Message-----
> From: Amps [mailto:amps-bounces at contesting.com] On Behalf Of Carl
> Sent: Dienstag, 2. Mai 2017 00:29
> To: 'Amps'; N1BUG
> Subject: Re: [Amps] 144 MHz GS35B update
>
> That tube also neeeds 3000-3500V before it shows good efficiency.
> My 2M 3CX1000A7 needs 80W for 1800 out at 3000V but it was a pull when I 
> got
>
> it with socket 35 years ago and still runs the same.
>
> Carl
>
>
>
> ----- Original Message ----- 
> From: "N1BUG" <paul at n1bug.com>
> To: "'Amps'" <Amps at contesting.com>
> Sent: Monday, May 01, 2017 4:50 PM
> Subject: Re: [Amps] 144 MHz GS35B update
>
>
>> There we go. After reviewing pictures of several other amplifiers using
>> this tube I removed one more turn from the coil on the tube side of the T
>> match. Input SWR is 1:1 and the amp is making over 600 watts out with 25
>> watts in. I plan to run it this way for a while before I go for the real
>> QRO.
>>
>> Paul
>>
>>
>> On 05/01/2017 02:40 PM, N1BUG wrote:
>>> I'm seeing more RF output with the new configuration, about 500W for
>>> somewhere around 25W drive. It appears I am going to have some fun
>>> getting the input SWR down but I guess everyone does. That's
>>> probably why there are so many slight variations on coil dimensions
>>> among the various plans.
>>>
>>> My first try with both coils having 5 turns 15mm ID, 20mm long
>>> resulted in minimum SWR of 3:1. My second try with 4 turns 15mm ID,
>>> 20mm long got it down to about 2.6:1. I am not sure whether to take
>>> another turn off both coils or perhaps just the one on the tube
>>> side. Many pictures of amps I have seen appeared to have less L on
>>> the tube side although I don't see this mentioned in any
>>> accompanying text.
>>>
>>> Paul
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>
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