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PGXL High SWR on 80 meters

Burch - K4QXX
Burch - K4QXX Member ✭✭
edited March 2020 in Power Genius XL Amplifier
I have been getting the high swr shutdown on 80 meters with my  PGXL.  I had two different 80 meter antennas running through an antenna tuner.  I took the antenna tuner out and plugged in each antenna directly to the amp.  My 80 meter dipole has a 1.4 swr at 3.900.  Once I get much past 500 watts, the amp jumps to 3.3 swr and shuts down due to high swr.  I also have a StepIR vertical with the 80 meter coil.  The swr on the StepIR runs from 1.3 to 1.7 swr according to the frequency.  Same issue with the StepIR.  Once I get to around 500-600 watts, swr jumps and amp turns off.  I have seen several others post similar issues with 40-160 meters.  40 meters and up work fine for me.  I am planning to put up my 160 meter inverted L soon and will see what happens with the amp.  I sure hope this can be fixed with firmware as I really don't want to send the amp back to Flex.

Burch
K4QXX

Comments

  • Steven WA8Y
    Steven WA8Y Member ✭✭
    edited November 2019
    This is likely to be caused by your antennas. Poor RF connections often work fine with low power. Check for corrosion in RF connections. If using baluns, they must rated for power. When they get hot, SWR increases. Also test the amp on a dummy load.
  • K0FLY
    K0FLY Member ✭✭✭
    edited November 2019
    What happens when connected to a dummy load?   If you contact Flex that will be their first question,   What happens with only one antenna connected to the amp?

    Does the problem occur with your external  ant tuner in the line.  If I read your post correctly the problem started when the ext tuner was removed.  You may have some grounding/common mode issues  that the amp  is sensitive to.

    Gayle K0FLY
  • Sergey KN7K
    Sergey KN7K Member ✭✭✭
    edited March 2020
    Nothing wrong with your antennas, there are several posts over last few weeks with the same issue.
    here is my 160m inverted V https://drive.google.com/open?id=1ESHURZc4z-ZXMXdta1k4-z6nDFJ1pKZN 

    open ticket with Flex

    Sergey, KN7K 
  • Bill - W9KKN
    Bill - W9KKN Member ✭✭
    edited November 2019
    Honestly, it's probably going to need to go back to the mothership, but it sounds like you may have had one of the low pass filters fail.
  • Burch - K4QXX
    Burch - K4QXX Member ✭✭
    edited November 2019
    It happens with the antenna tuner in-line and also when it's been removed.  Never had an issue with either antenna with my other amp.  Can easily run full legal limit on both antennas with my other amp.  
  • Burch - K4QXX
    Burch - K4QXX Member ✭✭
    edited January 2020
    Just got my amp back from Flex.  I hooked it up last night and transmitted on several different 80 frequencies up and down the band and the amp worked fine.  No more high SWR alert and fault after 400-500 watts.  Ran a little over 1000 watts with no issues.   Flex got the amp back to me pretty quick so thank you Flex radio for fixing the issue in a timely manner. 

    K4QXX
    Burch
  • Sergey KN7K
    Sergey KN7K Member ✭✭✭
    edited March 2020
    Good news Burch!
    Mine is arriving today after been at Flex for about month. Will test it tonight.
    Sergey, KN7K

  • K5PO
    K5PO Member ✭✭

    Was it confirmed that a low pass filter had failed in the PGXL? I just had this issue pop up this evening for 80 meters only.

    Cycled power on the amp. Same. Other bands unaffected. Same behavior on a dummy load.

    Two low-SWR antennas will transmit just fine direct from the 8600 but as soon as I bring in the PGXL on 80, I'm getting a "PGXL High SWR Detected by Hardware. Please Stop Transmission" message.

  • LZ2BE
    LZ2BE Member ✭✭

    50Ohm 500W harmonic load resistor is damaged. I had this problem a year ago and yesterday again.

    The good thing is the resistor is placed under Filter box cover and is very easy to replace. The bad thing is to find where to buy it :)

    73 Boyan

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