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testing and transporting an amp

Discussion in 'Amateur Radio Amplifiers' started by W9LF, Jan 13, 2021.

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  1. W9LF

    W9LF Ham Member QRZ Page

    Hello everyone

    I will be picking up an 8877 amp later next month and need some suggestions on testing the amp and then preparing it for travel. Specifically, I plan on testing the amp out at the sellers QTH and then removing the HV transformer and tube.

    What is the safest way to do to this? Not crazy about getting my arm across a HV capacitor that is still bleeding off voltage. Is there a safe time limit for ensuring there is no smoke left in the amp before doing surgery?

    thanks in advance for any help

    Carl de W9LF
  2. WA4SIX

    WA4SIX Ham Member QRZ Page

    A well insulated screwdriver with a cliplead is what I have always used to bleed off any HV area.

  3. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    If the unit has a plate voltage meter, watch to see it drop from full voltage to zero. If it does that, when it reaches zero it should be plenty safe.

    But to be sure, or in case the B+ is not metered, use a shorting stick clipped to the chassis and then touched to the B+ line (once unplugged!).

    You can "buy" these, like shown here: but I make my own out of a long wooden dowel with a small metal hook on one end, wired to a series string of 100K 3W high energy resistors* then to test prod wire with an alligator clip on the end (with the resistors heatshrinked over and tied to the dowel, near the hook end), which costs maybe $5 or so to build and they work fine.

    *These are readily available and look like this:
  4. WB3BEL

    WB3BEL Ham Member QRZ Page

    If you are just travelling by car, I would not worry about removing the transformer and tube. I'd get just get some help to move the box and amp, if you are not able to do it yourself, and put it on the back seat or floor if it will fit. If you have a big trunk or minivan, you could just wrap it in a moving blanket if you don't have the box.

    If it is a big rack mount behemoth or some homebrew contraption, then my advice might not be so good.

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