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Is this normal behavior? (Standing up my new PGXL)

Ok, my very first linear. I'm running on 117VAC until I finish pulling my 240VAC ckt from the panel box. I'm seeing something that isn't consistent with the user guide.

If I push the amp to over 400W output with my 6500 in Tune mode it stays there for only a couple of seconds and then drops to zero. Simultaneously, the fan starts screaming at a level just below Broadcast. My antenna SWR is 1.5:1 and my 6500 is generating 38W drive when this happens. There is no APC or Foldback indication. This just doesn't seem right. Shouldn't I be able to generate ~650W all day in this config?

BTW, if I backoff the drive to yield ~270W output the temp goes to 73C and the fan gets real noisy. 73C for only 270 watts??? Really? Is that normal?

Also, the PGXL box in SSDR is no longer showing data. (It used to.) The PGXL app displays normal data.

Any thoughts greatly appreciated.

73 Frank / WA3NHK


  • Bill NE1B
    Bill NE1B Member ✭✭✭

    Not normal. What band? Although I am running mine on 242 VAC, the only time my PGXL climbs above 70C is when I am on higher bands like 6 meters and the SWR is 1.5:1 or higher. My Log Periodic antenna is 1.5:1 and the amplifier heats up quickly on 50 MHz. On the other hand, my 6M7 yagi with a 1.2:1 SWR results in a cooler 50-60C temperature for long cycles at 1.3 KW. I usually run in "C" mode on FT8.

    Last night I ran a lot of DX on 40 meters and the amp ran cool at 42C and 1.3 KW.


    Bill, NE1B

  • fpmacko
    fpmacko Member ✭✭
    [{"insert":"Hi Bill\n\ntnx for the quick response. All was in 40m. I hope to have it running in 240 this evening. I had to run out to Lowe’s for Romex staples. \n\n73….Frank\n"}]
  • Mike-VA3MW
    Mike-VA3MW Administrator, FlexRadio Employee, Community Manager, Super Elmer, Moderator admin


    That sounds like you have an RFI issue and the Amp lost communication with the radio.

    Time to invest in a high power dummy load and test again.

    I still use the HeathKit version of this one from DX Engineering as it was a much better SWR sweep than my 1500 watt dry version all the way to 450Mhz.

    By using a dummy load, it gives you a very very good reference. You spent a lot of your amplifier. $100 more on a dummy load is a good investment.



  • fpmacko
    fpmacko Member ✭✭
    Hi Mike

    So I got off my **** and cabled up my big Bird load. No change with the PGXL panel in SSDR so it can't be RFI. Besides, the PGXL Windows app is running fine on the same PC as SSDR. I'll reboot the PC in the morning and see what happens.

    I'm gonna stand down on this issue until I finish my 240V ckt installation. Sometime Saturday morning. A little while ago I smashed my thumb trying to drive romex staples into 30 yr old petrified joists so I'm taking the evening off.

  • fpmacko
    fpmacko Member ✭✭
    Ok, so I can't say "****". Just add a trailing "t" to "but".
  • fpmacko
    fpmacko Member ✭✭
    Ok. Um good. Finally installed the 240V service and the PGXL is now operating like the beast I expected it to be. It seems that it just doesn't like operating on 120V.


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