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5000A Hum on AM Receive

Alan C
Alan C Member ✭✭
edited June 2020 in FLEX Series (Legacy) Radios
Flex 5000A - on AM receive I get a pronounced 'hum' (almost like a 60 cycle hum). Receives well on the broadcast band, but that background hum is there. This hum occurs on all bands in the AM mode.  Filter set to 6K  (default). I tried other filter bandwidths, with little difference. SSB and other modes are just fine (no hum at all).

Perhaps there is some setting that I am not aware of...

thx

Alan

Answers

  • Alan C
    Alan C Member ✭✭
    edited June 2019
    OK, the hum is not on all bands. on WWV 15Mhz AM - no hum. Broadcast band primarily
  • Ken - NM9P
    Ken - NM9P Member ✭✭✭
    edited June 2020
    I get that nasty hum even on my 6500 when the power lines behind my house are leaking profusely (like they are right now).  It seems to be coupling to the AM signal in some way.....
  • Alan C
    Alan C Member ✭✭
    edited June 2019
    Ken,

    Well, you are right on. I just checked 1450 AM with my Mark V - same hum!. Something local, no problem with the transceivers. Thanks for the heads up, indeed.
  • Ken - NM9P
    Ken - NM9P Member ✭✭✭
    edited June 2020
    I have an MFJ TNC whose wall-wart power supply used to couple into the rig somehow and put a hum on all the signals on my old IC-745. (1985-1993). When I pulled the wall wart the hum disappeared. I never figured out if it was re-radiating signals into the antenna or some kind of ground loop. You might check for this with equipment connected to your rig or sharing the same ground buss.
  • Alan C
    Alan C Member ✭✭
    edited June 2019
    Good tip, Ken, I have plenty of those wall warts running. I'll check them out. thanks!

    Alan, W4FBI

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