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PGXL output power jumping up and down

LA9GX Member ✭✭
edited August 28 in Power Genius XL Amplifier

My quite brand new PGXL have been heavily used for about one month now, no issues.
Then one morning I started to operate FT8, I notice that the power is jumping up and down.
lets say I am running 900 watts out, suddenly it can reduse output to appx 500 or 700 or, on rare occations, 0 w.
Now warning, no significant change in SWR.

Setup is Flex 6400M, PGXL, OM 10-1 antenna switch and a 4/5 el quad.
No changes was made since new.
FW 3.7.32

Running SDR 3.5.8

Tom, LA9GX


  • John WA7UAR
    John WA7UAR Member ✭✭✭

    What version of SmartSDR are you running Tom?

  • LA9GX
    LA9GX Member ✭✭
    I am using SDR 3.5.8
  • John WA7UAR
    John WA7UAR Member ✭✭✭

    I am just speculating Tom and throwing out different ideas…

    1. Maybe power input quality / regulation into the PGXL is fluctuating?
    2. Maybe one or more of the coax connections is loose? Can you measure the cable conductor (both to the antenna and also the short cable from the Flex to the PGXL) with a meter to check its length for any breaks?
    3. Maybe a ground connector from the PGXL is missing or loose?

    Good luck! I’m sure you will resolve it.

  • Mike-VA3MW
    Mike-VA3MW Administrator, FlexRadio Employee, Community Manager, Super Elmer, Moderator admin

    It is also a good idea to test this into a dummy load.

    If you don't own a 1500 dummy load, they aren't very expensive and DX Engineering have them at reasonable prices.

  • LA9GX
    LA9GX Member ✭✭
  • LA9GX
    LA9GX Member ✭✭
  • LZ2BE
    LZ2BE Member ✭✭

    Tom, I saw similar power fluctuations when I transmit close to TX passband limits below 300Hz or above 2600Hz. Probably you were working F/H and you answer to Fox station below 300Hz.

    73 Boyan LZ2BE

  • Bill NE1B
    Bill NE1B Member ✭✭✭

    Boyan, Good point! I have observed the same effect. To resolve this, I widened my bandwidth to 100 Hz Low, to 3200 Hz High on my Flex 6600. That eliminated the power fluctuations.

    73, Bill NE1B

  • LA9GX
    LA9GX Member ✭✭

    The amp is on it's way to Wimo for service.....

  • Kevin_1969
    Kevin_1969 Member ✭✭
    I had the same problem, so has several others, which boiled down too a variety of issues, from faulty transistors, poor soldering and failed power supplies. Absolutely unacceptable to have so many failures from something that costs this much.

    I switched over to Acom, currently awaiting arrival for my PGXL, which currently is in Texas being repaired for exactly the same fluctuation problems with output power.

    I had the same finger pointing at me, such as "it's your set-up", "It's RF getting into something", "We need to see your operating set up", blah blah blah

    Heaven forbid it would actually be an equipment failure, no , that never happens!

    After more then 40 years of using amplifiers, building a couple high power tube amps, etc... I was some what put off by the negative attitude towards my "lack of understanding" and that it must be my fault/installation/operating procedures.

    I have been using the Acom, my home brew pair of 3cx1500's, PWM AM transmitters, etc... without issue.

    The PGXL's are far from bullet proof.

    Good luck and I hope they repair it quickly for you.
  • LA9GX
    LA9GX Member ✭✭


    Yes, I must say I was a bit put off by the early failure, also having been warned by others.

    But the operating easy is very attractive ;-)

    So, no bad attitude when I approached them, just a message to ship it back.

    A costly thing here in Europe, about 200 USD on my part.

    I do belive they cover the return postage.

    Anyway, just bought an Amp Supply LK-800 as a backup ;-)

    So, lets see how they handle this warranty issue.

    73 de Tom, LA9GX

  • Kevin_1969
    Kevin_1969 Member ✭✭

    Hi Tom,

    Very good! Congrats on the back up Amp, I hope it serves you well. I did somewhat the same thing, I bought an Acom 1200S as a back up. Problem is I like it so much I think I will sell the other when it's fixed, Lol!

    I will be looking forward to your post on what they find as the issue/issues. I plan on posting as well once I hear something. This will be the 5th week since they have had it, with no reply yet on when it will hit the bench to be looked at.

    Yes they cover the return postage, that's what I was told by Flex.

    Good luck and I hope things work out that this will be the last trip for your Amplifier.

    73 de Kevin, W9FMC

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