Dentron Clipperton L rebuild

Discussion in 'Amateur Radio Amplifiers' started by KO4INE, Jul 1, 2021.

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  1. KO4INE

    KO4INE Ham Member QRZ Page

    Couldn’t find a forum for projects/rebuilds but since it’s an amp thought it would go nice here. I recently purchased a Clipperton L at a local hamfest that had sat for quite a long time. My father-in-law, who is also my Elmer said we needed to check some things before firing it up, and it’s a good thing we did. One cap on the power supply board plus the bleed resistors we’re all gone, so I bought a new kit from Harbach to put in it. The doorknobs are all in tolerance luckily. The both tank coils show some major heat from some hard drive over the years. The band switch had some arcing happen between the 10m connection and ground, which has since been repaired and we modified the band switch to keep that from happening again. Still had the original 572b tubes we are hoping are still good. I have stripped it down to just the transformer currently and going to bring it back to life gradually taking my time under the instruction of my father-in-law so I can learn while doing the work also doing some of the upgrades we have read about as well in the process. Here are some pictures so far, just waiting for some Corona dope and some #14 enameled wire I have ordered to come in to start putting it back together. I’ll post more pictures of the progress as I start getting it back together.

    Attached Files:

    N3RYB and KA9JLM like this.
  2. KA9JLM

    KA9JLM Ham Member QRZ Page

    Nice project. :)

    I have one with a bad power switch. It is welded ON. I just use a power strip. (Bad Me.) I did rebuild the power supply a few years ago.

    The factory L is good amplifier for a tube rig that can drive them. Tuned input is even more better, But a external tuner on the input can satisfy a SS transmitter.

    Have Fun. Save some smoke for later. :D
  3. W9GB

    W9GB Ham Member QRZ Page

    KA9JLM likes this.
  4. KO4INE

    KO4INE Ham Member QRZ Page

  5. VE2GCE

    VE2GCE Ham Member QRZ Page

    I have the successor to this amplifier, Clipperton QRO (the last one Dentron made).
    It is almost the same amplifier. The RF chamber looks almost identical to mine.
    The improvements they made were the following:

    1) Added a switchable lowpass network on the input to better match the transmitter.
    2) The 6.3 volt supply has been center tapped to address hum issue that W9GB mentioned.

    I changed the RF choke on mine, since I was using it on WARC bands and wanted to avoid any series resonances.
    Ameritron sells a WARC friendly RF choke at a reasonable price.
    KA9JLM likes this.
  6. VE2GCE

    VE2GCE Ham Member QRZ Page

  7. KO4INE

    KO4INE Ham Member QRZ Page

    Rebuilt the 160m side of the tank coil adding turns to it to help with the efficiency. Everything is starting to come together.

    Attached Files:

  8. DL3LK

    DL3LK Ham Member QRZ Page

    Or build a Input Bandpass Filter. No switching or tuning, only put it in the input line.
    I build it for my Dentron 160-10 witch is mostly similar to the Clipperton (4x 572B)
    Look on my website in the english part:


    Attached Files:

    Last edited: Jul 6, 2021
  9. KO4INE

    KO4INE Ham Member QRZ Page

    Got the plate choke and the parasitic suppressor board ordered from Ameritron. We were looking at just replacing the old carbon resistors in the original suppressors but found the board they used in the AL-572 and thought it would be a good upgrade to do along with the choke. Hopefully it will ship on Monday and not take forever to show up.
  10. W1QJ

    W1QJ Ham Member QRZ Page


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