[Amps] TL-922 Help

Thu Feb 24 15:54:50 EST 2005

I believe the RF Parts ZGs are fairly close the Eimac drive requirments -- I think the Amperex tubes needed more drive.  I used the RF Parts tubes in my 922 and they worked very well.  I had it running on 240V, and installed some of Rich Measures' mods.  I got about 1100-1200W on 10m, and 1400-1500 on 75 & 40m with 100W drive.  I don't remember the Grid/Plate I, though -- it's been too long.  

FWIW, I can get ~2kW out of my Henry 3K-A with ~100W drive on 75 & 40m with those same tubes.  The difference of course is the supply, since it puts about 3700-3800V on the plates of them under load.  It sits at 4kV idle.  But I have been quite happy with the tubes in both amps, I have run them pretty hard and they just keep making power.

Joe, N3JI

"Robert F.(Bob) Jones" <rfjones at ris.net> wrote:
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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