[Amps] Building 833 Amplifier. Hints and Suggestions?

[Edward Swynar]

Hi Greg,

The ARRL's "RadioAmateur's Handbook" for 1980 (I believe) features just such
an amplifier---in fact, the 833A in it actually graces the front cover...!

I, too, have an 833A that was recently given to me by a good Ham
friend---and like you, I've been mulling over the possibilities of building
a low band linear around it.

Do keep us posted as to your progress there, Greg, with my thanks in
advance...

~73!~ de Eddy VE3CUI - VE3XZ

***********************************


----- Original Message -----
From: "Greg Weinfurtner" <weinfurt at ohio.edu>
To: <amps at contesting.com>
Sent: Tuesday, March 16, 2010 1:18 PM
Subject: [Amps] Building 833 Amplifier. Hints and Suggestions?


> Hi all,
>          I am new to the list so be kind! I went through all of the
threads
> on amps at contesting.com concerning an amplifier using 833's and pretty much
> came up with very little usable information. Why 833's?  Why do I still
> deer hunt with a muzzle loader with just iron sites? Why do people still
> build tube regens?  Just 'cause I guess it is a challenge and the 833 is a
> magnificent looking tube all aglow!
>
>          I was an Electronic Design Specialist for Ohio University for
over
> 22+ years and have built a hybrid solid state 160 meter SSB/CW 100 watt
> transceiver (Using a pair of 6146's) from the ground up, (
> http://oak.cats.ohiou.edu/~weinfurt/160mrindex.html )including a 500 hz CW
> filter. Age is mid 50's and was in Tube/Solid State transition during
> college years. Yep, slip sticks to calculators to SMD's. BSS (Bachelor of
> Specialized Studies in Shortwave RF Engineering) is from 1994, so that and
> being an EDS helped keep me in the loop until I recently retired.
>
>          I have all the parts to put together 160 meter single band
> amplifier. I realize that it is a low mu tube of about 35, and would
> probably not make a great grounded grid tube... but maybe at 160 meters a
> pair of them could reach legal limit with less than 100 watts input?
>
>          I have 5 each of 833A pulls, with only 6 months of use. I got
> these from the engineer in charge and he said that usual pull time is at
> least over a year or unless some failure occurs.  But, the owner of the
> station demanded that he do it every 6 months no matter what the condition
> and he kept the 'like new' ones.  Yes they are old, 20 years or so.
>
>          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?
>
> 2 Grid driven with a 55 ohm, 75 watt non-inductive resistor to ground.
>
> 3 Pi output network or Pi L ? Or Link coupled output?
>
> 4 Operation is CW and occasionally SSB. Bias voltage on Cathode developed
> across about 60v Zener to ground?
>
> 5 Power supply is capable of 3000 VDC at 1 Amp.
>
> 6 Forced air cooling up from pressurized bottom chassis to box on top
> housing tubes and output components.
>
> 7 Tubes mounted in vertical position. Heat sinks for pin connections.
>
>
>
> Greg Weinfurtner AEE BSS
> NS8O
> 40192 State Route 689
> Meigs County
> Albany, Ohio 45710
> United States of America
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