[Amps] TL-922 voltage / bias

[Tom Prohigh]

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 at 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 at prohigh.com>
> To: <amps at 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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>
>