[Amps] Ameritron AL-1200 problem on 160 meters

[W7RY]

It sounds like a good first step is to buy or borrow a dummy load. Even a $30.00 hamfest special Heathkit Cantenna would work just fine.

73
Jim W7RY

  ----- Original Message ----- 
  From: k8dio at windstream.net 
  To: amps at contesting.com 
  Sent: Wednesday, November 26, 2008 3:55 AM
  Subject: [Amps] Ameritron AL-1200 problem on 160 meters


  Hi,

  I recently picked up a used AL-1200.  I tried to tune up the amp, on 160 meters, and have a problem.  I am using a TS-2000 as a driver and reduced the power, in the AM mode down to 5 watts.  I did this to sneak up on the input power.  I slowly brought up the power until I saw some grid current.  I put the meter in power output position and adjusted the Plate and Load controls.  I only get a small amount of rf output.  I am getting plate current though.  Even though my inverted L really doesn't provide a good load on 40 meters, I tried the same exercise on that band.  I was able to adjust the Plate and Load controls for over 1kw output so I know that the tube is okay.  Viewing the schematic, it appears that all of the output coils are used on 160 and capacitors C11 and C12 are brought into the circuit. If I am reading the schematic correctly, C11 and C12 are the only "fixed" caps brought into the circuit.  I measured the parallel C11/C12 caps and they measured 350 pf.  The low
    end of the caps is at ground when the band switch is in the 160 meter position so I know that the switch is working.  So, I am baffled at what the problem can be.

  I also have a question on the inrush relay K3. It seems that, during power up, K3 is only on for around .5 seconds.  Is this short time normal?

  Thanks,

  73, Lloyd   K8DIO

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