[Amps] TL-922 voltage / bias

[Carl]

Did you modify the bias circuit or check the voltage?

Carl


  ----- Original Message ----- 
  From: Tom Prohigh 
  To: Carl 
  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