Here are a couple of sources you may find at the library:
Radio Handbook, 22nd Edition, 1981 page 22.52-22.61 has
something that may be very close. It uses a directly grounded screen
that floats the cathode negative with respect to chassis to provide
screen voltage. It appears to be designed to go along with a 5W output
transmitter in another section of the book.
Radio Handbook, 16th Edition, 1962 page 654-661 has another
using a 4CX1000A. This one uses the screen bypass cap built into the
SK800 socket. This uses a grid swamping resistor for 75W drive. I have
often thought about building this one!
Then, there is the Collins 30S-1. You can probably get a manual
from one of the manual reprint vendors.
Mike, W1NR
BTW: The 4CX1000A and 4CX1500B are virtually interchangeable.
Leigh wrote:
>
> Hello Amp People,
>
> I acquired a very nice home-brew amplifier recently and I am in
> the process of figuring out what I need to do to get it on the
> air. Unfortunately, it came with no documentation, ugh! It is a
> grid-driven tetrode design using a 4CX1500B tube. It has a
> filement supply and an adjustable bias supply built into the RF
> deck. It is built like a battleship, uses vacuum variables, a
> manly band switch, and is fully metered. It appears to only
> require HV + screen voltage to operate. Unfortunately, my
> limited amp experience is with grounded-grid amps and I have a
> few questions for anyone on the list here with significant
> experience with such a beast.
>
> I guess the biggest question I have is in regards to the
> requirements of the screen supply. There appears to be no screen
> by-pass resistor in the RF deck so I'll assume the builder (have
> no idea who it was) included that in his screen supply. The
> Eimac data sheet states 70mA for this resistor so I guess its
> value should be around 5k ohms? What is the recommended size of
> this component. I would guess 5 watt would be large enough but
> maybe I am not considering possible failure modes? Some
> references I have seen state that HV should be applied before the
> screen voltage so I'll assume it is a good idea to apply screen
> voltage with the TR relay activated. Any thoughts on a
> recommended screen supply circuit. I wouldn't think with the
> screen bleeder that regulation is required and I was thinking of
> using a choke input filter (anyone have a ~4-5 HY 350mA 400VDC
> filter choke lying around?).
>
> None of my references have any constructed amps described using a
> grid-driven 4CX1500B design (or any grid-driven tetrode for that
> matter). Anyone out there have a good reference of a successful
> design that I could use for my reference. I will be using a 3000
> VDC 1 amp supply that I already have built up for high voltage.
> The HV xmfr in this supply has a 375V tap that I will use to
> power the screen supply so that is no problem.
>
> Any other words of wisdom to help me out here.
>
> Thanks for your time reading this and hopefully you won't spend
> too much time helping me out here (time is a precious
> commodity).
>
> 73 de Mike
> K7PI
> Mercer Island, WA
>
> --
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--
**************** Give Every Man His Dew **************
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mailto:w1nr@eecorp.com
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