The 833, while magnificant looking for a glass tube, sort of industrial
1940s look, was not a particularly high frequency tube. You would have
troubles making it play at 10 meters, for instance. Neutralization will
be needed in all cases on HF, and will need to work on reducing the lead
inductance to the grid and filaments. But for 160 meters, it would work
fine. Bob Henry in Albuquerque, NM, built a single 833 amplifier few
years ago, I need to find his email. He had some troubles getting gain
or efficiency very high, if I am not mistaken.
> Message: 3
> Date: Tue, 16 Mar 2010 14:18:43 -0400
> From: Greg Weinfurtner <weinfurt@ohio.edu>
> Subject: [Amps] Building 833 Amplifier. Hints and Suggestions?
.....
>
> I would prefer help from someone who has actually used the 833 in
> some type of RF circuit. But anyone with engineering experience with a
> behemoth of this type knowledge would be great! I plan to set up a web
> page and with my progress to keep those helping informed of my advancement
> into the past!
>
> Characteristics for the 833A are
> at: http://oak.cats.ohiou.edu/~weinfurt/833A.pdf
>
> ************************************************************************************
> Plan.
>
> 1 Two of them in parallel or Push-Pull?
RAYTHEON RAN THEM IN P-P ON MEDIUM WAVE IN THE RA-1000.
MOST OTHER BC RIGS USE TWO IN PARALLEL FOR A KW. AGAIN, THIS WAS AT <1.6
MHz.
> 2 Grid driven with a 55 ohm, 75 watt non-inductive resistor to ground.
PICK A CLASS OF OPERATION, LIKE B? YOU WILL PROBABLY WANT SOME Q ON THE
INPUT TO SMOOTH OUT THE GRID
CURRENT AFFECTS DURING PART OF THE RF SWING.
> 3 Pi output network or Pi L ? Or Link coupled output?
WHATEVER YOU LIKE
> 4 Operation is CW and occasionally SSB. Bias voltage on Cathode developed
> across about 60v Zener to ground?
EITHER OK.
> 5 Power supply is capable of 3000 VDC at 1 Amp.
GOOD VALUES, SIMILAR TO BROADCAST RIGS
> 6 Forced air cooling up from pressurized bottom chassis to box on top
> housing tubes and output components.
YES, GOOD IDEA
> 7 Tubes mounted in vertical position. Heat sinks for pin connections.
ABSOLUTELY.
>
>
> Greg Weinfurtner AEE BSS
>
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