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SWL with my Flex 6300

N3CHWN3CHW Member ✭✭
I am running 3.0.27 with my Flex 6300 when I try to listen to AM Broadcast beyond 7.300 mhz my RF gain reduces so much that it is not possible to listen to the broadcasts. Has anyone else had this issue?


  • Ken HansenKen Hansen Member ✭✭
    edited June 2019
    To clarify, is this an issue on any frequency above 7.300 MHz, or only outside the amateur bands?
  • N3CHWN3CHW Member ✭✭
    edited June 2019

    Sorry for the late response  but the weekend had me doing other things.
    Using the db signal readings on the Right side of the screen. When I move outside of the Top Side of the Amateur Bands the signal levels drop as follows.
    160m -18db approximately
    80m   -18db  "
    40m   -10db  "
    20m   -18db "
    Is this normal? It makes SWL more difficult.

  • edited June 2019
    Don't see that with my 6400 and V2.5.1.
  • Burch - K4QXXBurch - K4QXX Member
    edited June 2019
    I'm not seeing that here either on a 6700.  I was just listening to SW last night in the 5Mhz and 7Mhz range.
  • Steve K9ZWSteve K9ZW Member ✭✭✭
    edited June 2019
    @N3CHW - Perhaps you are seeing the gain pattern of your antenna(s) as your listening frequency moves from resonant to non-resonant frequencies?



  • N3CHWN3CHW Member ✭✭
    edited June 2019
    Steve, in each band the method I used was not changed. I switch to the band in question in the upper part of the ham band and slowly moved the A slice up in frequency and suddenly bam! at the end of the ham portion the noise floor as shown on the right side scale changed down 10 to 18 db as I reported as if a filter was inserted.

  • Doug HallDoug Hall Member ✭✭
    edited June 2019
    Look at the preamp setting just before you go out of the ham band. Then look at the preamp setting just after you "cross the line" to outside the ham band. Did it change?
    Doug K4DSP

  • Greg N8GDGreg N8GD Member ✭✭
    edited June 2019
    I have a 6300 here, and I don't see this behavior as you described at all.  I even kicked in the RF Gain (under the ANT tab on the left hand fly out panel) thinking it might affect things as I tuned past the band edges but saw no difference there.  The RF Gain did increase the noise floor about 3 db or so when it was engaged, but did not change when tuning past band edges.
  • N8AUMN8AUM RETIRED Member ✭✭
    edited June 2019
    Do you have Sig gen ?
  • Greg N8GDGreg N8GD Member ✭✭
    edited June 2019
    OK.  I just found something.  If I have the ATU disengaged (off, or greyed out), I do not see the behavior you describe, but, if you engage the ATU (button is blue), as you tune outside the ham band, the ATU will disengage.  If your antenna is non-resonant and needs the ATU to be engaged for good SWR within the amateur band, even for good receive performance, it will not have the advantage of being tuned once you leave the ham band.  I would guess that an external tuner would resolve that issue.  I personally do not see the change in noise floor when the ATU disengages here, but my antenna is most likely different than yours.
  • N3CHWN3CHW Member ✭✭
    edited June 2019

    No I do not. What is your suggestion if I did?

  • Stan VA7NFStan VA7NF President Surrey Amateur Radio Communications Member ✭✭
    edited June 2019
    No one has mentioned that the spectrum is broken into frequency range groups and when you cross a range boundary all the settings change to that range portion.
    This means antenna selection, filters, preamp level, AGC_t, and more change.  Once in a new segment, set these up.
  • N3CHWN3CHW Member ✭✭
    edited June 2019
    Thanks All for leading  me in the right direction. I found the answer to my issue. About a month ago I installed a antenna switch with a BCD interface and connected it to the radio via a USB to BCD cable. For the sake of brevity I won't explain much more except to say that radio now controls the antenna selection. Ops, except when the Slice falls outside of the ham bands then it puts all antennas to ground. 
    Thanks Again to the community.

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