[AMPS] The Monster Breathes

[km1h @ juno.com]

On Sat, 20 Sep 1997 22:57:24 -0700 "Ron Angle (AB6ZX)" <dom@shocking.com>
writes:
>Some of you have been so gracious as to provide advice and support 
>during my amplifier rebuilding projects of the last six months. Now it 
>is time for an update.
>
>The Monster, a 40-inch high homebrew linear, was constructed in the 
>mid-sixties. It uses a pair of 4-400A's in grounded grid with very old 
>circuitry. No safety features, completely ungrounded with floating AC, 
>bad bleeders and all.
>
>Tonight I fired it up for the first time. It breathed, groaned, and 
>glowed in the dark! The one tube with the greenish glow at its base 
>seemed to cook properly (more on this in a future post). The plate HV 
>meter does not indicate the correct voltage so I am not sure of the 
>full load plate voltage. I was able to get an accurate reading of 1200 
>VDC on the PS with 35 VAC on the primary supply from the Variac. Some 
>extrapolation puts the plate voltage possibly near 4 KV.
>
>With initial loading the amp drew approximately 400 ma with a grid 
>current over 100 ma. The indicated key down output was about 600 
>watts. 
>
>Question:  What would be the expected efficiency of this amp, 
>considering the tubes may be 15-20 years old?


Efficiency is the same this year as in 1966 Ron. With good tubes expect
60% or so.
At full bore it should do 1200-1300W out with ease at 2500-3000V; 1500W
at 3.5KV.

 
>I am pleased with the initial results and brief on-air tests on 75M 
>SSB yielded good reports on the signal quality with very low drive 
>(MIC gain setting of 2 on my TS-820S). Besides the need to completely 
>redo the control wiring, relays, safety features,etc., the only major 
>problem is heat. Idling current is 135 ma which produces considerable 
>heat; a zener in the filament return line is my next project.
>
>Again, thanks to all for their posts. I compare this project to 
>rebuilding a sixties' big bore Mustang. It's big, ugly, but still fun!


More like a small block 351C .  You need 4-1000A's to equate to a 429
Cobra!

Have fun    Carl  KM1H

>
>73
>
>--
>FAQ on WWW:               http://www.contesting.com/ampfaq.html
>Submissions:              amps@contesting.com
>Administrative requests:  amps-REQUEST@contesting.com
>Problems:                 owner-amps@contesting.com
>Search:                   http://www.contesting.com/km9p/search.htm
>

--
FAQ on WWW:               http://www.contesting.com/ampfaq.html
Submissions:              amps@contesting.com
Administrative requests:  amps-REQUEST@contesting.com
Problems:                 owner-amps@contesting.com
Search:                   http://www.contesting.com/km9p/search.htm