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PGXL concerns on 6 meters

I have had some concerns about the operation of my PGXL on 6 meters so Flex volunteered to have it returned to the factory for test and evaluation... I got it back after about a week with an email stating that it performed as well as any other PGXL and that there was nothing wrong with it. I hooked it up and noticed I still have the same challenges on 6 meters and since the factory states it is operating correctly, I can only assume other PGXL owners operating on 6 meters are having the same challenges and I would like to know how you are handling them. Here are my challenges:

Driving the amp with a 6700 the max output of the PGXL is 900 watts with the Id at 45amps

With the amp in standby, the 6700 indicates the input to the amp SWR is 3.1 while the output is 1.2... both input and output measured with the 6700 meter, Bird 43 and an Alpha 4510 and the antenna is a Alpha 2100 lab dummy load.

On any band EXCEPT 6 meters I can run FT8 at 1500 out for several cycles before the fans even turn on...On 6 meters the fans come on almost immediately and before the cycles finishes the the temp. jumps to around 70 degrees C and the fans go into METO... they are so loud that SSB can not be used as they drown out the mic. and the amp is on the other side of the room.

All these challenges only happen on 6 meters but since the factory has tested and certified the amp as being in proper running condition, you must have the same challenges and I am asking how you

have been able to work around these.

Thank you , bc


  • Bill AB7AA
    Bill AB7AA Member ✭✭✭

    Hi OM,

    I haven't worked 6 M in years so I thought that I would try out my PGXL and see if I could dupe your problem. I don't have a dedicated 6M antenna but I always knew that my 7-30M LPDA would easily accept power on 6M with a 1.2-1.3 SWR throughout the band. Anything that is 17M might have an acceptable SWR there because it is an odd harmonic. So I went ahead and gradually brought up 1500 watts with no problem with 50 watts drive. I did not want to keep it there too long because I don't know what ferrite material is in the LPDA 4:1 balun and could easily burn it up. But my PGXL worked fine there.


    Bill AB7AA

  • WX7Y
    WX7Y Member ✭✭✭

    I ran my PGXL for the first time for any length of time at about 1KW on 6 Meters today after adding my new TGXL and it runs great and I have no issues with SWR on the Input to the AMP here, I'm sure you have changed out your Jumpers and such.

    My station consists of Flex 6700, PGXL, TGXL, Ant. Genius, and a couple of my antenna's tested where my 50MHz thru 2.5GHz Log-Periodic, Wide band loop, and Dummy load.

    Absolutely NO issues and the band was wide open today and made over 20 contacts in a couple hours.

  • AH0U
    AH0U Member ✭✭

    Well that is not anything like what I get.. works great on 160-10 but on 6 it is a really different matter.

    Tnx fer the feedback es 73, bc

  • Bill NE1B
    Bill NE1B Member ✭✭✭

    What is the Warranty period on the PGXL? It doesn't seem to be published.

    I just had my first return to the factory after LDMOS failure. I had 2 months of great operation before failure. I operate primarily on 6 meters and had also noticed greater heat generation on that band. There is still the thermal expansion/contraction "creaking" sound.



  • AH0U
    AH0U Member ✭✭

    I really think that the 6 meter part of the PGXL is an after thought and that it really is not designed to be a true 6 meter amp[..... when you operated 6 meters, what power did you get out of it?? With my 6700 cranked up full I get around 900 but the the fans are screaming...

  • Sergey KN7K
    Sergey KN7K Member ✭✭✭

    Here we go, captured today few TX cycles in FT8


    Sergey, KN7K

  • Bill NE1B
    Bill NE1B Member ✭✭✭

    I also easily got 1500 watts out.

    51 watts in 1,000 watts out

    56 watts in - 1200 watts out

    65 watts in - 1500 watts out

    I accidentally put out 1750 watts on 6 meters for a transmission before I looked up at the monitor. It would be nice to have a settable alarm for the regulatory limit points.

    I have 2 antennas that have different SWRs. The PGXL backs off a bit with the higher SWR on my T11 Log Periodic.

    T11 LPA is 1.5:1 on 6 meters, but PGXL will put 1500 watts into it with more drive

    6M7 M2 is 1.2:1 on 6 meters and the PGXL easily has more power output

    The PGXL root cause of the failure was attributed to over- torque on a **** which held down one LDMOS device. A photo shows the **** in the ceramic area of the LDMOS. The QC department has been notified.

    73, Bill NE1B

  • KD0RC
    KD0RC Member, Super Elmer Moderator

    Thanks for the update Bill. It is always good to know what the actual problems are as opposed to all the speculation. In any event, I am glad you got your amp back and that it is up and running again.

  • WX7Y
    WX7Y Member ✭✭✭

    I only drive mine on FT8 to about 1KW on FT-8 but that is just me with signals in the +20 from most stations, My drive for full legal output power is approx. 45 for full legal output on 6M, This does depending on my Antennas though +- 10%.

    My Amp would do Something like yours when I ran it on my HF-AUTO tuner with the tuning solution it came up with a good SWR and couldn't operate it on 6 until I got the TGXL Tuner on line just this week.

    If you have had it back to flex and they found nothing wrong then possibly your Antenna or Tuner is not up to ****, The Harmonic load will warm up in the AMP very quickly and the FAN's run at high speed, maybe this is your case after all SWR is not the only thing that effects an Antenna and feedline.

    The AMP was definitely designed for 6M and was not a afterthought.

    I would work with flex and see if they can log into your computer and then into the AMP they may be able to tell you what exactly to look for or if there really is a AMP issue, I know they can do a lot of Diagnostics this way as they did with me back in 2018 when I received mine.

    Good luck and hope you find the solution, I relies how frustrating it can be.

  • bahillen
    bahillen Member ✭✭✭

    Try using a 50 ohm dummy load and compare the behavior.

    if you are seeing a 3:1 anywhere something is strange.

    Try checking the amplifier gain at different levels and see if it is changing. That woul I declare something is shutting back the amplifier.

    I also tune the antenna tuner on my 6600 to the amplifier and seems to get more consistent readings. The SWR measurements are not perfect with non 50 loads and reactive loads.


    Bill W9JJB

  • AH0U
    AH0U Member ✭✭

    Sergey...If my PGXL worked anything like yours, I'd be the happiest guy on Earth but mine is not anywhere near that...at 900 watts with 75 watts drive my temp jumps to 60 in seconds and the fans drive me out of the shack... 6 meters is a bust with the PGXL here

  • Bill AB7AA
    Bill AB7AA Member ✭✭✭

    I had a similar problem with my original PGXL, but down on the lower bands. I could not get rated power from it unless the SWR was very low and would SWR fault for SWR's above about 1.7. It had strange SWR behavior that appeared like it could be an antenna issue or arc-over. Adding just 17 ft of coax completely changed its response on 40M and then would allow almost any SWR. It turned out not to be my antennas or feeds. I worked with Flex for about a year on the problem including many Teamviewer visits from them including the design engineer in Montenegro. I even opened the case with their blessing and gave VNA plots of the antennas from the plane of the filter input section. After its second trip to Flex with no conclusive analysis, I powered it up and the finals blew. I think that there was either a faulty connection or component in it producing reactive responses.

    Let me comment about the integrity of Flex. They gave me a completely new amplifier with a brand new 2 year warranty. It has worked perfectly ever since (almost a year) including 6 meters.

    My recommendation to you is to keep on it and play ball with them and they will take care of you.


    Bill AB7AA

  • AH0U
    AH0U Member ✭✭

    I wish those whop are having the same problem as I would open a ticket rather than contacting me of line... There is a problem here and if you don't speak out about it, Flex wont fix it. Below is an email I just received:

    Hello Bruce,

    I was reading your comments on the flexradio web site regarding the PGXL

    on 6m.

    Mine is heating like the WS7M's PGXL according to the video he uploaded

    june 3th.

    With meffa ON, in Contest mode and using an icom 7610, I'm running 750

    watts on 6m. I can go up with 1KW (and maybe more) but the final is

    going hot very quickly ( not the harmonic load ).

    I tried with a dummy load : same thing.

    When looking on the video of KN7K when he is running 1500w on 6m with a

    temperature staying below 50°C, I'm far away of this...

    Did you run more tests on 6m ?

    Thank you


    valéry, f5idj

  • David Decoons, wo2x
    David Decoons, wo2x Member, Super Elmer Moderator

    Yes, If you are having issues and the suggestions here do not help, open a Help Desk ticket.

    My 5 band Yagi surprisingly has a 1.25:1 SWR on 6. I have been running the amp about 400 watts on FT8. The amp heats up quicker than 20 meters but who knows what the complex impedance really is. I am limiting to 400 watts to be safe. Worked 5 new countries this week. Not bad for no real 6 meter antenna. Brazil was the furthest.

    Wish I could still physically go up on the roof, I would have added a small 6 meter Yagi below my 5 band Yagi.

    Dave wo2x

  • AH0U
    AH0U Member ✭✭
    edited July 2021

    did open a ticket and have suggested to the others who have contacted my off line and have the same challenge to also turn in a ticket.... maybe with all of us having the same issue, Flex will come up with a fix... tnx fer your input

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