[Amps] TL-922 Help

[Robert F.(Bob) Jones]

Hi gary,

Actually I am now running the amp with HV on new tubes but no drive.I plan on doing this for 24 hours.The previous tubes were cooked in also and lasted 3 years under severs usage (many contests,etc).The previous  tubes never came up to full power during the 3 years where the previous Eimac tubes had no problem.I have heard the ZG tubes require more drive than the Eimacs but my 850 is good for 80 watts only and I don't want to push it any harder.I am hoping I can recover full power by tuning the input,getting the ig up or changing the bias,if needed for the ZG's.I don't want to try any of this without some expert advice,hi.

Interestingly since I posted this request I found the Kenwood benchmarks for ig,lp and power out in the Kenwood service Manual.
At 80 watts in and 1KW out,the plate current should be 600ma,the grid current should be 190ma and I have never seen this with the ZG's.My max ig is 100-125ma and plate current is 400-450ma based on band of operation.This is with no ALC control connected.

I'm betting that if I can get the ig up to 190-200ma this will fix my problem.My question is how to do this with 80 watts in.

It's a real leaning experience for me and this group has been a big help.Thanks for your comments.
----- Original Message ----- 
  From: Gary Smith 
  To: Bob Jones ; Amps at contesting.com 
  Sent: Thursday, February 24, 2005 11:48 AM
  Subject: Re: [Amps] TL-922 Help


  Did you give the new tube a reasonable amount of time to "cook in ?"
  Do recall that rf parts suggests at least 24 hours, did note when I installed my new rf parts 3-500, after 24 hours of warming and then putting it to usage my output was lower than what I expected.  Then, not expecting, and three week later output power had risen to rated amp rf output levels. 
  73,
  Gary... wa6fgi
    ----- Original Message ----- 
    From: Bob Jones 
    To: Amps at contesting.com 
    Sent: Thursday, February 24, 2005 6:54 AM
    Subject: [Amps] TL-922 Help


    A few quick questions:

    1.In transmit mode with no drive,I have 50ma idle plate current on CW and
    100 ma on SSB.Is this OK and if not how to adjust?Book says should have
    twice this level.Zener checks OK,100 volt supply is OK,both relays check OK.

    2.Using the RF Parts ZG tubes and 80 watts drive I cannot drive the amp to
    full output.I notice SWR on TS-850 is higher than with the Eimac tubes and
    even placed a tuner and different lengths of 50 ohm coax between the 850 and
    amp,this helps but still only 400 ma plate current under full load.Plate
    volts drop from 2000 to 1900 from no load to full load.Ig rarely gets above
    100ma.Have tried tuning input coils using Kenwood method but tuning is very
    broad and has little effect on power out.Any ideas and a safer way to tune
    the input coils?I do have a MFJ Antenna Analyser and thought I could use it
    to look at the coils??
    Note:Amp is running on 220 vac primary power.

    3.Am presently installing Rich measures supressor kit and hope this helps
    the parasitic problem Just lost grid resisters and chokes when one tube went
    cathode to grid short,saved the filament transformer though.

    Any help on item 1 and 2 would be appreciated and I'll have the amp ready to
    put back on the air.

    Thanks and 73,
    Bob
    W0OXJ

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