Did you modify the bias circuit or check the voltage?
Carl
----- Original Message -----
From: Tom Prohigh
To: Carl
Cc: amps@contesting.com
Sent: Friday, February 12, 2010 10:34 AM
Subject: Re: [Amps] TL-922 voltage / bias
There are 2 tubes in the TL-922. The grids are DIRECTLY connected to ground,
I removed the caps and chokes and also put in a second ground wire from VC1.
This eliminated some arcing/parasitics I was having. The tubes are original
Eimac 3-500Z not 3-500ZG. The color on the plates is fine, no color at idle
and red/orange at full drive. I do get about 600-700W out on CW, but only
about 1000 key down on SSB on 20M. 80M is somewhat higher
Tom - AB3FL
On Fri, Feb 12, 2010 at 10:30 AM, Carl <km1h@jeremy.mv.com> wrote:
That idle current is fine for 1 tube and the voltage drop is excessive.
Start by measuring the grid chokes for an open or looking for color on both
plates.
Carl
KM1H
----- Original Message ----- From: "Tom Prohigh" <tomp@prohigh.com>
To: <amps@contesting.com>
Sent: Friday, February 12, 2010 9:47 AM
Subject: [Amps] TL-922 voltage / bias
I have recently aquired a TL-922. It is on a stiff 240V line which
actually
measures 245V. No load voltage on CW is 2200 and on SSB is 3100. Under
full load the CW drops to 1900V @ 600ma and the SSB drops to 2400V @
800ma.
Is there really suppose to be this much drop? It has the original 200uf
caps in it and I was thinking about replacing them with 560uf units. Also
the grid bias on CW is 60ma and on SSB 120ma which seems a little low.
thanks
Tom - AB3FL
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