[Amps] HELP Modifications for a Kenwood TL922

[on4aef at base.be]

  It is not a question of money or to put some other types of tubes.
  It is a question of using only one 3-500Z in this amplifier and what I
have to change to realise this not more !
  Of course I have to change the filament transformer into a 5VAC version
because originally both 3-500Z's are in series on 12VAC !! 

  Regards Jean ON4AEF.



On Tue, 26 Jan 2010 15:21:29 -0500, "Carl" <km1h at jeremy.mv.com> wrote:
> A. A new 3-500Z costs around $150
> 
> B. The grids are not grounded in a TL-922.
> 
> C. I dont think there is top clearance for a 4-400
> 
> Carl
> KM1H
> 
> 
> ----- Original Message ----- 
> From: "Colin Lamb" <k7fm at teleport.com>
> To: "BEHIELS JEAN-PIERRE" <ON4AEF at base.be>; <amps at contesting.com>
> Sent: Tuesday, January 26, 2010 2:50 PM
> Subject: Re: [Amps] HELP Modifications for a Kenwood TL922
> 
> 
>> Hello Jean:
>>
>> I see the problem as follows:
>>
>> You got an amp that uses two 3-500 tubes, but you only got one 3-500
>> tube.
>> An additional 3-500 tube would cost more than the amplifier and you
want
>> a
>> cheap solution.
>>
>> You can use two 4-400 tubes ore even 4-250 tubes and should be able to 
>> trade one 3-500 for two of those tubes.  In Europe, there are QBL 
>> equivalents to the 4-250 and 4-400 tubes.  The tubes will fit in the 
>> sockets.  These tubes are tetrodes, but the socket will ground both the

>> screen and the control grid.  These tubes like higher voltage and will
>> not
>> run as much power - but they will work.
>>
>> 73,  Colin  K7FM
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