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Low output on 15 meters

Mike J
Mike J BSSE, MSAE, MSEEMember ✭✭
I have low output on 15 meters. Only 15 meters. The RF Power (in red) on my screen (center) indicates 100 watts. In my TX Band Settings menu shows "RF PWR" 100, the same as all my other bands. The PWR knob on the radio will raise and lower the output but will only show 30 watts on 2 separate watt meters along with the radios watt meter. I am sure I have some setting somewhere that is causing this, I just can;t find it. I read over just about all the messages here about low power and it seems the universal answer is to do a reset. There has to be a reason or a setting that is causing this. Any ideas? (other than a global reset)

Comments

  • KD0RC
    KD0RC Broomfield, COMember, Super Elmer Moderator

    Hi Mike, have you tested into a dummy load? If you get the same results into a dummy load, then I would submit a help desk ticket.

    If the dummy load operates normally on 15 (and all bands), then either the feedline or antenna is suspect.

  • Mike J
    Mike J BSSE, MSAE, MSEE Member ✭✭
    I checked it on a dummy load before posting this.
  • David Decoons, wo2x
    David Decoons, wo2x Member, Super Elmer Moderator

    What mode are you testing with? What model external meter? Some meters are not very good peak reading meters.

    Set the tune slider to 100 and use the Tune button to test with a carrier.

    If you have the capability, check the DC voltage at the connector at back of radio while transmitting at 100 watts carrier to see if there is a voltage drop. You can also use the program FRStack to monitor voltage in the radio.

    Dave wo2x

  • Mike J
    Mike J BSSE, MSAE, MSEE Member ✭✭

    It doesn't matter what mode. CW and SSB are both low. My meters are fine. (besides the Daiwa I use in line, I have a Calibrated Bird and Calibrated Struthers) I have a full test bench. My amperage draw is appropriate when running 100 watts on 20 meters and it is appropriate running 30 watts on 15 meters.

  • Trucker
    Trucker Member ✭✭

    Sounds like Help Desk time.

  • Mike-VA3MW
    Mike-VA3MW Administrator, FlexRadio Employee, Community Manager, Super Elmer, Moderator admin
    edited March 24

    A few things.

    Good on the dummy load. What is the DC voltage when measured at the back of the radio while transmitting in FM at 100 watts?

    If it is over 13.8V, please open a support ticket. helpdesk.flexradio.com

    If less, then you need to figure out where the voltage drop is.

    73

  • Mike J
    Mike J BSSE, MSAE, MSEE Member ✭✭

    Thanks for the info. I am not at the radio right now and wont be until later this evening but other than the TX Band Settings menu, are there any other settings in hidden or plain sight menus to check for reference? Mike, are you talking about the input power supply to the radio? My power supply will not allow over 13.8vdc. (or any other voltage other than what I have it set for with a small margin for voltage drop) My power supply has visual Volts and Amp. The voltage and amps are both where I would expect them to be with 30 watts output.

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

    The voltage at the radio, or better yet, from the internal metering on the radio would really help to try and isolate the problem. Just because the power supply indicates 13.8 volts doesn’t mean it is truly delivering enough voltage to the PA of the radio. Measuring the voltage with a Fluke meter (or other good quality digital volt meter) at the back of the radio during RX, then when transmitting will show if the power supply has a voltage drop . Then comparing to the internal meter available via FRStack, Flex Meter, or Node Red (3rd party software) will show if there is a voltage drop across the Anderson Power Pole connector or internal fuse in the radio.

    testing with a carrier (Tune slider at 100) is far more accurate than SSB or AM. The internal watt meter in SmartSDR is not a good peak reading watt meter. I do not know the accuracy or peak reading of the Daiwa. The Bird 43 needs to be retrofitted with a mod for peak reading capability.

    Try the suggestions presented and report back.

    If using a carrier via Tune at 100 and DC voltage internal in radio (install FRStack 3) is at least 13.8 volts on TX, then open a Help Desk ticket.


    Dave wo2x

  • Mike J
    Mike J BSSE, MSAE, MSEE Member ✭✭

    With the contest coming up in a few hours, I went on 17 meters and found I have MAX 40 watts out on 17. I have NO voltage drop at the radio and the amperage pull is where it should be at 40 watts on 17 and 30 watts on 15. To reference that, I have 100 watts out on 20, 40 and 80 with appropriate amperage draw. I have 3 antennas to choose from. Both my 15 and 17 meter SWRs without any tuners is close to 1:1 so that is ruled out. Now to go find where I open a ticket.

  • Geoff AB6BT
    Geoff AB6BT Member ✭✭✭

    Did you measure the internal voltage as David suggested using the internal meter available via FRStack, Flex Meter, or Node Red (3rd party software) ?

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

    @Mike J

    Can you share with us the voltage reading? There are a few ways to retrieve it as outlined above. The actual number is important as it is 100% related to RF output.

    With WPX happening tonight you could also do a reset of the radio and see if that clears up your situation.

    I just did a test on my 6600 remote and this is what I have.

    I have tune set to 100%, my radio voltage is 13.2VDC and the RF out is 93 watts on the LP-100A (Calibrated) into a 1500 watt dummy load. FRStack is reading the internal meters in the radio. If I was to make the standard operating voltage of my power supply 15V, which is well within the operating specs of the radio, then my RF output would be higher, but for the 0.3 db difference between 93 watts and 100 watts, it isn't worth the effort. :)

    The wattmeter in the radio (and it is a physical watt meter) is showing 89.6 watts.

    I don't deny you have an issue, and if you do, the support team will want to see this data just to make sure the problem isn't environmental as over 95% of the problem reported are related to something in the environment that can be resolved quickly. This is why the specifics are so important.

    We also want to avoid a radio being sent in that turns up as no trouble found as it is impactful to your operating time and even if the radio is under warranty, there could be a charge for the bench testing time.

    Anyway, this is why the important questions.


  • John KB4DU
    John KB4DU Member ✭✭✭

    Even with relatively short power leads(less than 1 foot) I get almost 1 volt drop between ps and flex at 100 watts. Of course this doesn’t explain why one band would be different.

  • Mike J
    Mike J BSSE, MSAE, MSEE Member ✭✭

    Sorry for my tardiness. I ran the program Flex sent me and it confirmed my measurements. The 6400M went back to Flex and has returned. They replaced the LPF module.

    All is well :-)

    73 Mike

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