[Amps] Has anyone ever actually build an 833A linear?

[Carl]

Performance will be similar to a 250TH or any other large glass low mu 
1930's tube used as a SSB linear. Low mu by current standards anyway. Expect 
IMD in the mid to high -20's which is right in the same area as sweep tubes 
and 12V SS transceivers. It is also an inefficient tube above 20M, some say 
40 especially for pulls.

With sufficient swamping and attention to layout neutralization may not be 
required but its physical construction is a detriment to good isolation. A 
250TH or 304TH/TL is easy to stabilize.

I remember a PP pair of 750TH's used only on 75M SSB running 7500V and a 
30L1 as the IPA driver in the early 60's down in MA.

If you simply "must" use 833's then good luck. Im sure it could make ER 
Magazine (-;

Carl
KM1H


----- Original Message ----- 
From: "Gary Schafer" <garyschafer at comcast.net>
To: "'Mike Waters'" <mikewate at gmail.com>; <amps at contesting.com>
Sent: Wednesday, December 19, 2012 1:48 PM
Subject: Re: [Amps] Has anyone ever actually build an 833A linear?


> You will need a push pull type of grid circuit in order to neutralize 
> them.
> The bridge type circuit will not work well.
> If you just swamp the grids with a resistor and use a step up transformer 
> it
> will take more drive than it is worth.
>
> 73
> Gary  K4FMX
>
>> -----Original Message-----
>> From: Amps [mailto:amps-bounces at contesting.com] On Behalf Of Mike Waters
>> Sent: Tuesday, December 18, 2012 4:24 PM
>> To: amps at contesting.com
>> Subject: Re: [Amps] Has anyone ever actually build an 833A linear?
>>
>> Well, two grid-driven 833Cs in parallel may or may not be as linear as
>> the
>> best expensive ceramic triodes in G-G. But if it's linear enough not to
>> make my signal much wider, it's good enough for me. If it generates bad
>> key
>> clicks and spurs, then I'll build another one with the GS-35B I have,
>> and
>> say we learned something.
>>
>> I plan on swamping the grids, and probably using a broadband step-up
>> transformer to get the grid voltage needed with 100w drive. With a
>> string
>> of 18v 10w zeners for grid (not cathode) bias. I already have all those
>> components; why not breadboard something and try?
>>
>> 73, Mike
>> www.w0btu.com
>>
>> On Mon, Dec 17, 2012 at 4:58 PM, Carl <km1h at jeremy.mv.com> wrote:
>>
>> > Its not a very linear tube for SSB, great for AM.
>> >
>> > Carl
>> > KM1H
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