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[VK2ICJ]

Hello All,

I have a TL-922 wired for 240volts (norm here in Aus) MY IG meter was not working but I was easily able to get 8-900 watts out (I only do CW) of 75watts in to a Dummy load.  I took it to a local ham (who came recommended) and he fixed my meter issue.  I can now read my IG when transmitting which never goes over 200mA (It didn't move before).   My HV is 2000 CW and 3000 SSB.  Now though when I put 50Watts in I get 500 watts out and taking the exciter from 50 to 100 watts maybe nets me another 100 to 150 watts for a total of 650 watts out.  When I contacted the ham who worked on it he stated that is how it was when he worked on it.   I'm thinking this is not the norm for this Amp.  Does this sound like the tubes are going soft or is there something in the fix of the IG metering circuit which could possibly explain my readings?   Thank you.

73  Chris vk2icj

[W1QJ]

Seems suspicious it dropped power after a repair but we don’t know what he did.  The SSB CW switch is moot in the USA.New amps use full plate voltage under the new rule.

[ZS5WC]

 :)Hi Chris, are you running with ALC line connected?.
I have an TL-922 with vacuum relays , soft start , soft key, all the earthing mods done.
I get 600w out on CW position and 50 watts drive.
The grid current reading is done via the cathode circuit, so maybe decoupling cap. is faulty or disconnected.

73 de William
ZS4L / ZS5WC

[VK2ICJ]

I do not have the ALC Line connected

[W9IQ]

Can you get an exact and detailed description of what was done to the amp by the person that repaired it? It should include parts replaced and settings tweaked.

Don't rule out the possibility that the repair guy didn't properly tune your amp when repairing it. The tubes may now be soft.

- Glenn W9IQ

[ZS5WC]

This might be of interest to you:
I have tried this myself. Although I have my doubts a soft tube can be reconditioned, I have used this method to determine if tubes are good.
Obviously if the correct anode voltage is applied, and anode current cannot be obtained, you have a soft tube.
Two 20A variable smps supplies needed and croc. clips and multimeter.
let desk fan blow over tube whilst testing.
https://pa0fri.home.xs4all.nl/Lineairs/Tubes%20reconditioning/tube%20reconditioning.htm
73 de William
ZS4L / ZS5WC

[VE7RF]

This might be of interest to you:
I have tried this myself. Although I have my doubts a soft tube can be reconditioned, I have used this method to determine if tubes are good.
Obviously if the correct anode voltage is applied, and anode current cannot be obtained, you have a soft tube.
Two 20A variable smps supplies needed and croc. clips and multimeter.
let desk fan blow over tube whilst testing.
https://pa0fri.home.xs4all.nl/Lineairs/Tubes%20reconditioning/tube%20reconditioning.htm
73 de William
ZS4L / ZS5WC

Interesting method that PA0FRI used.   W8JI used a different method, with amp on it's lowest B+ setting ( or feeding 120 vac into the 240 winding of the plate xfmr).    Then the small lab supply hooked up, with positive to chassis..and negative to cathode ( CT of fil xfmr.)   Then with a few volts of adjustable bias, the tube can be tweaked to suck loads of plate current ( elevated idle current).   Typ a min of 800-900 vdc required on the anode to do this procedure.

PA0FRI's method requires NO B+ used at all.

[W1QJ]

Haven’t heard back from the OP and gettering a tube isn’t the topic!!  Many hams don’t understand a simply concept about amps.  Many question that the radio swr on there antenna is 1 to 1 but when they use the amp it’s 1.5 to 1 or something other than the antenna 1 to 1.  In the OP’s case I wonder if the input swr is poor.   Solid state radio with a conservative swr fold back will tend to stop outputting much more than 50 watts at around a 1.5 swr.  You can Jack your radio to 100 watts put as soon D you transmit into the amp it will fold back to (0 watts. This goes with the OP’s problem that increasing drive power doesn’t yield more power.  GROUNDED GRID AMPLIFIERS MUST HAVE THE LOAD ADJUSTED EACH TIME TBE DRIVE IS INCREASED.  You can’t load at a low drive and then pull the drive wsy up!! The load must be compensated each time drive is raised.

[VK2ICJ]

In regard to the SWR I was using a dummy load which was reading 1 to 1 on the radio with the Amp in bypass.  When turning the Amp to transmit the SWR on the radio increased but not more than 1.5. I was using a TS870 as the exciter.  ALC was not connected.  I contacted the Ham who repaired the amp in the first place and he stated it was working fine when it left his place.  I did not ask for the specifics of the repair. 

Haven’t heard back from the OP and gettering a tube isn’t the topic!!  Many hams don’t understand a simply concept about amps.  Many question that the radio swr on there antenna is 1 to 1 but when they use the amp it’s 1.5 to 1 or something other than the antenna 1 to 1.  In the OP’s case I wonder if the input swr is poor.   Solid state radio with a conservative swr fold back will tend to stop outputting much more than 50 watts at around a 1.5 swr.  You can Jack your radio to 100 watts put as soon D you transmit into the amp it will fold back to (0 watts. This goes with the OP’s problem that increasing drive power doesn’t yield more power.  GROUNDED GRID AMPLIFIERS MUST HAVE THE LOAD ADJUSTED EACH TIME TBE DRIVE IS INCREASED.  You can’t load at a low drive and then pull the drive wsy up!! The load must be compensated each time drive is raised.