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6500 Power fluctuates

6500 power out varies significantly (80/30/60/20 watts as an example) and rapidly on all bands/modes. SWR and input voltage is steady.


  • WK2Y
    WK2Y Member ✭✭
    edited December 2020

    What happens if you reduce power? Does this happen from a cold start or after you have been operating a while? Do you have a dummy load you can try?

  • JohnS
    JohnS Member
    Hi, Bob. Thanks for the response. The power fluctuates at all power levels. The fluctuation happens from a cold start to later after operating awhile. It seems, however, to be most noticeable during cw contests (I operate in a lot of contests) and when on 15 meters (I use a Steppir DB18e antenna). I do have a dummy load, which the power also fluctuates at the same characteristics just like using with an antenna (and all antennas). And I have experienced this significant, wide rapid power fluctuations with new and old coax and with several and no connectors. The power supply I use is a small 25 amp switching device with continuous voltage and amperage readings in full view on my desk. I've had this 6500 for about a year (purchased used from another ham) and it worked quite well up until the last two months.
  • WK2Y
    WK2Y Member ✭✭
    edited December 2020

    Doesn't sound RF related. Something is cutting in and out quickly. The only other thing I can think of would be to clean and check all the power supply connections and wiggle the connector on the back of the rig. I have heard of that going intermittent and I know I have connectors I have to clean on a regular basis. I'll bet you already have done that, right? Let's let other chime in with some other diagnostics, but from what you say here, it sounds like it could be time for a ticket.

  • VE7ATJ_Don
    VE7ATJ_Don Member ✭✭✭

    Hi John.... does the power out fluctuate if you hold it for a few seconds in key down mode? Or is it between key presses?


  • ka9ees
    ka9ees Member ✭✭✭

    I don't think your power supply has enough current capability.


    Ed KA9EES

  • Erika - KØDD
    Erika - KØDD Member ✭✭✭

    I had too small of a power supply on the radio and it cause weirdness. Now have a linear 35 amp running only the radio and that has stabilized out. However the Anderson power pole on the radio does get weird I have 14.1v on the buss in the radio read by DDUtil v4.0.1.09 and displayed, and when the connector weirds out it will drop to 14.0v just sitting there and then I know there's higher resistance in the cable and you can feel it heat under power.. When I do a 100w key down the DDUtil voltage monitor says 13.5 when things are working OK. But that is dropping quite a bit across the power cable and internal wiring.

    When I was in the computer manufacturing business we ALWAYS had voltage sense lines AT THE Card bus's that told the power supply to crank up the voltage to maintain a constant voltage at the card racks. It might be a good deal to go to a 4 pin HD plug instead and supplies that will monitor sense and auto adjust voltage.

    I did buy a can of non-residue electrical contact cleaner for the power connectors and that helps the voltage drop for a while, but they do go right back into high resistance contact mode. APP connectors are easy to use but not the best device at these current loads. I agree a 25 amp supply is light... But this might not be your only issues. Some RF in the shack can cause a LOT of problems and is probably the number ONE problem with these radios and clean stabile signals.

  • JohnS
    JohnS Member
    Thank you all for your thoughts and comments. Since my post I have changed out the power supply with a similar switching supply and the 6500 seems to be happy - so I am happy. It may have been the ps or my cleaning the right connections (they didn't look bad), but it is well now. Thanks again.
  • Dave-N9CHM
    Dave-N9CHM Member ✭✭

    I would suggest using the K9DUR SDRMonitor app so you can constantly watch the radio supplied voltage. It also monitors radio temp.

  • JohnS
    JohnS Member
    Interesting - K9DUR monitor, thanks. How fast is it? Probably hard to measure.

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