Yaesu FT-1000MP and the Ameritron 811

Discussion in 'Amateur Radio Amplifiers' started by KE6GRN, Apr 22, 2016.

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  1. KE6GRN

    KE6GRN Ham Member QRZ Page


    I have an issue with my Ameritron AL-811 amp. I have had the amp serviced, and I replaced all the 811 tubes with matched Taylor tubes. I have checked D-16 diode and it is good.

    I am using the Yaesu FT-1000MP for the exciter. The most power output I am getting is 250 watts on 10 and 12 meters, 400 watts on 15 and 17 meters, and 475 watts on 40, 80, and 160 meters. This is with the power output on the Yaesu FT-1000MP at a full 100 watts.

    I have tried this with the ALC of the radio connected and disconnected. The ALC on the amp is turned up all the way. Any help you can give me will be greatly appreciated.


    Michele, KE6GRN
  2. W8JX

    W8JX Ham Member QRZ Page

    You should never need anywhere near 100 watts drive for a AL811 to make 450 watts (any more shortens tube life) as it should make that with 40 to 50 watts drive. Check input SWR to amp for starters and reduce drive power too. I never run my rig at 100 watts anymore. I run it at 50 watts barefoot as that is same drive level I use for amp and I can merely turn it on when needed.
  3. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    When you are using the amp with the output from the Yaesu adjusted so the amplifier just reaches its "maximum" output power, what do the Plate Current and the Grid Current indicate on the Ameritron meter? Write down the readings.

    The ALC control on the amplifier does absolutely nothing if the cable is not connected to the transceiver.:)
  4. N8SAC

    N8SAC Ham Member QRZ Page

    I have a 811 an run the driver at 56 watts max. Gives me 475 to 500 out. The amp was new in 1992 and is on the second set of tubes. If you take care of it . It will give you great service.
  5. G0KVL

    G0KVL Ham Member QRZ Page

    I run the same set up, a 1000mp and an Ameritron 811 (3 tubes) with no ALC, and only need about 50w drive to get a good 400w
  6. N2OTG

    N2OTG Ham Member QRZ Page

    Maybe a problem with the tuned input of the amp? I had a similar problem with my 811. If you have an antenna analyzer, you can measure SWR at the input of the amp while tripping the amp's antenna relay. Or, your rig may have an onboard, SWR meter. Either way, the relay must be tripped to get a valid reading. Good luck.
    AA7QQ likes this.

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