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Broadcast station on 40m spilling into 40m Ham Band

Don Weeks
Don Weeks Member ✭✭
On my 6600, I am hearing a SW AM Broadcast station out of South Carolina at 40 over S9 and above. When they play music and in some cases talk, the entire ham band down to 7.150 noise floor raises up and down with the music. And in many cases stations at 7.260+ are drowned out or there is additional signal coming in over or with their voice distorting it. Someone online suggested adjusting the VFO and bandpass but I don't see a way to do that or I have not dug deep enough in the manual for this? 


  • John KB4DU
    John KB4DU Member ✭✭✭✭
    edited January 2020

    A few things to check.

    1) Is the Flex in WIDE mode, if so close the other panadapters so that there is only one open. This will enable  the bandpass filters, greatly increasing the selectivity of the 6600.

    2) Enable the TNF filters and set one over the offending signal. Procedure is in the manual.

    3)  Click on the mode (LSB) and select a narrower bandwidth for the slice, maybe 1,8.

    Let us know if any of these make a difference.


  • Don Weeks
    Don Weeks Member ✭✭
    edited January 2020

    I will look at this when I get home. TNF is something I can add for sure. The LSB mode is narrow but the signal coming from the SW station is narrow. I believe it is coming in around 7.320. I will look into WIDE mode.
  • Ken Wells
    Ken Wells Community Manager admin
    edited March 2020
    A few things to check:

    1) If the offending station is overmodulating, or has extremely sharp crossover transitions, these will mimic an impulse interfering signal.  This can trigger your WNB (Wideband Noise Blanker) if the WNB setting is high, which will pump the noise floor, and often send pseudo spurs up and down the band.  I have experienced this with Radio Havana.  Turning WNB OFF or down, may help.

    2) Be sure that you are not using preamp gain on 40 Meters.  It is unnecessary, and only reduces your dynamic range, which could make you vulnerable to extremely strong signal interference.
    This combined with zooming in your panadapter a bit and making sure that your radio is not in "Wide" mode can help.

  • WX7Y
    WX7Y Member ✭✭✭
    edited June 2020
    Build or buy a Broadcast filter and install it in the Antenna lead, Much better to get rid of the RF at source getting into the radio then to put a band-aid  or try to filter it out if it is that strong.
    Unfortunately the 6600 doesn't have a receive loop to install a Low power Broadcast filter like the 6700 has so the filter you build or buy needs to switch out of line during Transmit so you'll probably have to build a Relay switch that runs off the PTT Keying output.

    here are some on Amazon https://www.amazon.com/Flamingo-AM-Broadcast-Bandstop-Applications/dp/B079CMB44V/ref=sr_1_2?keywords...
    or https://www.amazon.com/Broadcast-Reject-Filter-RTL-SDR-Blog/dp/B01N9SHS7P/ref=sr_1_4?keywords=AM+broadcast+band+filter&qid=1578669759&sr=8-4
    or the great looking 11th order filter https://www.amazon.com/broadcast-reject-filter-order-enclosure/dp/B074S6X9HF/ref=sr_1_6?keywords=AM+...

  • Doug Hall
    Doug Hall Member ✭✭
    edited January 2020
    More sources. Neither of these requires bypassing on transmit - just put them in line with the Flex.



    Doug K4DSP

  • Craig_KØCF
    Craig_KØCF Member ✭✭✭
    edited January 2020
    Won't help. His interfering station is a 40 meter Shortwave broadcast station, probably just above the top of the 40 meter ham band. These filters are for the 500 kHz to 1.7 MHz AM broadcast band.
  • Bill -VA3WTB
    Bill -VA3WTB Member ✭✭✭
    edited January 2020
    And if the signal is going into the band pass, not much you can do. The 6600 has about the best filters around for signals out of the band pass.
  • caroline
    caroline Member
    edited January 2022
    The 6600 has better filters for out-of-bandpass signals than other antennas that's for sure, I even listen to certain radios like this, for example. https://www.radiofmdance.com

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