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AL-811 Problem

Discussion in 'Amateur Radio Amplifiers' started by KD6TR, Dec 19, 2013.

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  1. KD6TR

    KD6TR Ham Member QRZ Page

    Hi All. I have an AL-811 that I bought used from another ham. It worked fine for several months. Now when I fir it up the HV reads fine. When I switch it to Ip and apply drive, - - nothing! It doesn't recognize the drive. The red LED doesn't light and nothing on the meters. I moved and transported it in the back of my Jeep. It perhaps got a little shaken in the move. What should I check and How?? Thanks!
  2. KO6WB

    KO6WB Premium Subscriber QRZ Page

    First of all with the amplifier turned on but no cables connected to it, measure the center conductor of the RELAY phono plug.
    You should have about 12VDC from the center to the chassis ground.
    If you have the 12VDC try shorting the center conductor of the RELAY phono plug to chassis ground. The amplifier should key and be placed in the XMT condition.
    Since you have no drive going to the amplifier, you should read the idle current of about 2 divisions on the Ip meter.
    Now if it doesn't have the 12VDC in the RELAY center conductor then you have a power supply problem, connection or some other problem with the voltage doubler on the 6.3VAC filament line.
    Could also be caused by the STBY/OPR switch as well. The Ameritron switches are know to be, well, cheap.

    Oh, one more thing....Check and make sure the tubes haven't been displaced during the Jeep ride. That's not the reason for it not going to XMT but it could be a problem.

    Hope this helps
    Last edited: Dec 19, 2013
  3. WA5DTY

    WA5DTY Ham Member QRZ Page

    OM you did not mention what you are driving the amp with. Some tranceivers have a switch in the menu that must be turned on to get the Amp to key. Perhaps that switch ( menu item 39) on KW TS570 for an example. Might try that. What are you using for, if any, interface. Need a few more pieces of information for diagnosis....Thanks and Merry CHRISTmas.....
    73's Sam WA5DTY
  4. KD6TR

    KD6TR Ham Member QRZ Page

    Tnx to all! Problem was an open in the keying line from the xmtr.
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