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The temperature rises, the SWRs increase ... isn't it strange?

Greetings to all and thanks to those who can clarify the anomalous behavior of my Power Genius XL (fimwere 3.6.24)

Since July 2022 I am a happy owner and this is my first experience with an amplifier.🤗🤩

My set-up is a Flex 6600 with a dynamic antenna (3 EL 6mt - 40m) placed at 8m above a sheet metal roof.

In 30 meters, due to the effect of the underlying roof, the SWRs are normally a little higher than in the other bands (1.8 at a minimum -USA direction ) and vary according to the pointing of the antenna.

During the QSO the PGXL does its job and the internal temperature rises, is it normal for the SWRs to rise too ?????

I made a video of a QSO in FT8 where you can see that after 1min and 30 sec the internal temperature reaches 47.5 ° C and the SWRs rise from 1.8 to 2.8 !!!!😣

In the second video it is the next qso, the internal temperature has returned to 44 ° and the swr to 1.8, during the qso the same thing is accessed again, I think it is not a correct thing.

 Before opening a tiket and maybe having to part with my new and trusted friend, can someone kindly give me some clarifications?

Thank you thank you very much

73 IZ1XEE Piero

Best Answer

  • Stan VA7NF
    Stan VA7NF Member ✭✭✭
    Answer ✓

    My toroid in question is a DXE 3KW but it heats up on 80M cw 1000W out. I don't like that but is just the facts.


  • Larry _ NY8T
    Larry _ NY8T Member ✭✭✭

    If you are using a balun it could be over heating causing swr to rise (Ihave experienced this in the past on certain bands) and also causing amp temp to rise. If your not already, you want to use MEFFA for ft8, I see about 10 degrees c lower temps with MEFFA enabled.

  • Stan VA7NF
    Stan VA7NF Member ✭✭✭

    I agree, there is likely an antenna toroid that is heating. I see this at 1000W CW into a balun "rated" at 3KW. FT8 is full power (400W in your video?) for 10 seconds.

  • Piero Ferrua
    Piero Ferrua Member ✭✭

    Thank you Larry (NY8T) and Stan (VA7NF), for your immediate response and demonstrated competence.

    I confirm that I have a toroid estimated for 3000 W.

    I have to check but I remember that by default the MEFFA is also inserted for use in DTGI UP (FT8). I am sure I have checked the PGXL programming.

    Stan, the second video serves to demonstrate that when the PGXL drops below 45 ° the SWRs lower and rise again with use.

    The FT8 is a low power system, so I tend to use as little as possible to make me feel (Flex at 4W and PGXL at 400W) where I need it.

    I will ask the manufacturer of my antenna for an explanation what kind of toroid was put in when I extended my 3 El from 6-20 to 6-40 meters.

    For information, the tests were carried out with an ambient temperature in the antenna of 28 ° C.

    Thanks again for the replies, the most cordial 73 from Italy.


  • Piero Ferrua
    Piero Ferrua Member ✭✭

    Dear Stan VA7NF,

    I will hear the manufacturer of the antenna but if this is the case I do not expect anything good ...😪

    Only the cold season will help in the dissipation of the heat produced, now in Italy it is really hot about 7-9 degrees more than the norm and I live in the north.

    My antenna is a 2EL in 30 and 40, and 3EL in 6-20, so I have two torids which are activated by a relay depending on the required band.

    Rightly I have no temperature increases using the 6-20, while I noticed a slight temperature increase on 40 meters. Rightly 30 and 40 are under the same torus but the 40 have a more favorable initial chord (1.2) and the roof has a lesser influence.


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

    I have created a support ticket for you.

  • Piero Ferrua
    Piero Ferrua Member ✭✭

    Thanks Mike,

    before bothering Flex I wanted to make sure I wasn't wrong somewhere or setting.

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