Amp Repair in southern california

Discussion in 'Amateur Radio Amplifiers' started by KK6ZPD, Jan 15, 2020.

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  1. KK6ZPD

    KK6ZPD Ham Member QRZ Page

    looking for someone that could repair a kenwood tl-922 in the socal area
    anybody know of anybody?
    thanks tibor kk6zpd
     
  2. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    Can you describe what's wrong with it? (That is, what doesn't it do that it should be doing?)
     
  3. KK6ZPD

    KK6ZPD Ham Member QRZ Page

    The ig meter is not working the rf Meter works hv meter works high-voltage 3500k Low-voltage 2300........... also ip meter works .......I think my ip plate tune knob might be off because when you set the radio 7.220 and the plate knob to The center of the dial in 40meter you almost have to turn the plate knob almost to 80 m to tuneup The amp and the most I can get out of it in CW mode with a CW tone is around 550 watts with a proximately 55watts of driver The load knob is approximately 3 And the Ip is 0.5ma shoot I might be doing something wrong I don’t know I’m taking it easy thought

    And this is into a dummy load keep in mind
     
  4. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    It's not "3500K," but if the HV meter really indicates 3500V, I suspect the metering resistors have drifted, because it's supposed to be 3000V in SSB and 2000V in CW. Almost certainly either the wrong primary transformer tap is selected (at the jumper block) or the metering is off, which would be a very common thing.

    The front panel "band" indications on the PLATE tuning control aren't very meaningful. As long as the capacitor tunes smoothly and you can peak output power (and dip plate current) using that control, the markings aren't important.

    On CW, when the Ep should be 2000V, getting 550W output with 55W drive is exactly normal: That's 10 dB power gain, which is what it should have, and normal efficiency since when it's switched to "CW," DC power input is limited to 1000W. At 55% efficiency, that's 550W output.

    Don't ever switch the CW-SSB switch with the amplifier turned ON. But other than the Ig meter not working, everything else sounds completely normal. Have you removed the cover and inspected the switch (amp turned off and unplugged)? May just be a dirty or oxidized switch contact.
     
  5. KK6ZPD

    KK6ZPD Ham Member QRZ Page

    I haven’t really inspected the switches yet

    Ill take a look at it.....

    but I did remove the cover and blow all the dust out of it

    I’ll take a look at the switch in the IG Maybe the contacts are bad

    I’ll also be posting some pictures for you guys
     
  6. W1QJ

    W1QJ Ham Member QRZ Page

    Just want to say that I fully agree with Steve. The amp seems to be working perfectly. The dial adjustment can be altered to make it to whatever you want. The Ig not working is probably a switch or wiring problem.
     
  7. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    Great!

    Sounds like it's actually working fine. If this amp is "new" to you (although they are all quite old), you're lucky it seems the tubes are fine, and now that they're around $240 each that's a big savings if you don't need to buy any.

    Blowing dust out can (sometimes) also blow dust where you don't want it, like onto switch and relay contacts. When I service amps, I don't "blow" the dust out, I usually vacuum it out and use a soft paint brush to assist steering the dust towards the vacuum nozzle -- this isn't necessarily "better," but it's a bit more controlled and helps prevent blowing dust into tiny spaces where it shouldn't be.

    But besides dust, just ordinary oxidation can prevent switches from working properly, and a teeny droplet of DeOxit or similar can help. To apply such a solvent, I use a toothpick or similar to hold just a tiny drop and place it where it needs to be, as opposed to "spraying" it, which can get the solvent on places it shouldn't be.

    In any case, I'll bet your metering resistors for the voltmeter have drifted low in value, which is very common and happens with lots of amplifiers -- that will drive the HV meter readings higher than they should be and make the meter indicate a higher voltage than it really is. Very easily fixed, if you want to fix it.
     
  8. N7WR

    N7WR Subscriber QRZ Page

    Don't take this as a critical comment but it appears you may be a relatively new ham and this may be your first amp. Hopefully you are aware of the safety precautions when working on an amp. The voltages which may be present if the proper precautions are not take can be lethal.
     
  9. KF6LU

    KF6LU XML Subscriber QRZ Page

    Contact John KF6I, good thur QRZ, he's in Placentia so close to Riverside.
    Does great work at reasonable price. His company is Island Amplifier and web is
    islandamplifier.com He works on all linears.
     
    KK6ZPD likes this.
  10. KK6ZPD

    KK6ZPD Ham Member QRZ Page

    i just drop the amp off at his house hes going to go through it........ fix it and do all the upgrades to it..... fix the ig gound the grid and so on
     

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