[Amps] TL-922 voltage / bias

[TexasRF at aol.com]

Tom, I am not familiar with the terms "v bias" and "r bias". Are saying the 
 zener bias diodes have been replaced with resistors?
 
73,
K5GW
 
 
 
In a message dated 2/12/2010 9:40:18 A.M. Central Standard Time,  
tomp at prohigh.com writes:

Only mod  was V bias to R bias.  At key down, there is 7.5V at the zener.
Maybe  I should do the diode bias or get a 5.1V zener, or maybe just the old
tubes  are a little soft

On Fri, Feb 12, 2010 at 10:38 AM, Carl  <km1h at jeremy.mv.com> wrote:

>  Did you modify the bias  circuit or check the voltage?
>
>  Carl
>
>
>
>  ----- Original Message  -----
> *From:* Tom Prohigh <tomp at prohigh.com>
>    *To:* Carl <km1h at jeremy.mv.com>
> *Cc:*  amps at 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 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
>>>  _______________________________________________
>>> Amps mailing  list
>>> Amps at contesting.com
>>>  http://lists.contesting.com/mailman/listinfo/amps
>>>
>>
>>
>
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