Ameritron AL80B Replacement Parts HELP!!

Discussion in 'Amateur Radio Amplifiers' started by NP2KW, Apr 26, 2020.

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  1. NP2KW

    NP2KW Ham Member QRZ Page

    I need some help with this. I had a power mishap on my electrical meter base that blew my amplifier power supply board (and my refrigerator and 65 inch projection tv) many years ago. While doing a major cleanup of my garage yesterday, I found the amplifier neatly boxed and sealed and it still looks new so I decided to repair it myself. I never sent it to repair to Ameritron because shipping from and back to the Virgin Islands would have cost close to buying a good used one. Anyway... I opened it up and saw 2 parts that were obviously fried, these were:

    - RFC1
    - C28

    Upon further inspection with my multimeter, the following parts showed continuity:

    - C40
    - D17

    Also, the white tube with the thin red winding that's connected to the 3-500Z Tube has burnt traces along different areas of it's winding ( is this the "Plate Choke" ??, please clarify).

    Now this is where I need help,.... After downloading the AL80B manual with parts list, none of these parts show up on the list. I have also looked at pictures of AL80B boards online and none of the boards on those look even close to what mine looks like. And coincidentally, the only picture I found that matches exactly what my board looks like is not from an AL80B, but rather the AL-572 ( !!?? ). So I downloaded that manual, and guess what, the parts don't show up on that list either!! (WTF!!!). I would hate to throw this in the trash, it looks brand spanking new!! There isn't a single scratch or blemish on it! I couldn't find any serial number on the amp nor any identifying number on the power supply board, but I do know, from the previous owner, that it was bought new in 1994. Help please.
  2. K7TRF

    K7TRF Premium Subscriber QRZ Page

    It certainly sounds like you're talking about the plate choke. The plate choke is several inches tall, is made of ceramic material and wound with very thin enameled wire and the top of it solders to the parasitic suppressor which connects to the anode cap and the top of the tube.

    Photos of the inside of your amp would help a great deal in terms of verifying exactly what you have and what parts you need. Ameritron still sells replacement parts for most of their amps including the AL-80B so if you can verify exactly what you have you should be able to source the parts by schematic callout directly from them.
  3. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    When the plate RF choke (and that is what's described) has burned areas that's a really bad sign and usually when that self-destructs, so did other parts of the amplifier -- often including the tube itself.

    I don't know what is meant by "mishap on the electrical meter base" but if your AC line voltage surged up to something much higher than normal voltage, that could destroy the power transformer and there's only one. Should have blown the fuses also. Were the fuses blown?
  4. NP2KW

    NP2KW Ham Member QRZ Page

    Here's some pictures: Plate Choke.jpg PB.jpg Power Supply Board.jpg
  5. NP2KW

    NP2KW Ham Member QRZ Page

    I just uploaded some pics,.. notice in the closeups that the winding on the Plate Choke is cut, and notice the missing C28 and the partially blown off REC1. Thanks for your help!!
  6. NP2KW

    NP2KW Ham Member QRZ Page

    Here are the pics, notice the broken winding on the Plate Choke and the missing C28 and partially broken REC1,.. the fuses were not blown, and the "mishap in my meter base was caused by a large Salamander that grounded itself with one leg of the Utility power inside the meter base.
  7. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    I see the pictures now (I didn't see them at first! - took time to download.)

    Oh, an animal (or anything) shorting out one phase of the line shouldn't have really hurt the amplifier; a short inside the 3-500Z can cause a lot of damage, all reparable, and shouldn't take out the power transformer, which is by far the most expensive component in the amp.

    Someone else may come up with replacement P/Ns in the meantime, but if they don't, I'll get them for you tomorrow.
    Last edited: Apr 26, 2020
  8. NP2KW

    NP2KW Ham Member QRZ Page


    Attached Files:

  9. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    I finally saw them, about 30 seconds after my earlier post. They were large images that took more time to download than the text.:p
  10. KD0CAC

    KD0CAC Ham Member QRZ Page

    Some better pictures - out of focus ?

    REC1 next to the missing C20 appears to have a wire floating , hopefully the laying around for a long time is the cause of the dust / dirt etc. - this can lead to electrical arcing , should do a through cleaning if you do repair .
    Also looks like corrosion .
    Waiting to see if anyone can match you pictures to the actual amp ?

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