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
|