[Amps] 144 MHz GS35B update

Tue May 2 06:50:30 EDT 2017

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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