IC705 USB Noise issues

Discussion in 'General Technical Questions and Answers' started by DM5TT, Nov 21, 2020.

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  1. DM5TT

    DM5TT Ham Member QRZ Page

    Hey All!

    I'm having serious issues with USB noise using my Icom IC705.

    My entire 144 MHz and 70cm bands is covered with small spikes up to S5.

    Interestingly the noise is getting boosted as soon as I start WSJT-X and the CAT-Control is taking over.

    Things I tried for now:

    1. Adding a ADuM4160 isolator to the USB path. Didn't help - checked the device twice: Ground was isolated.
    2. Adding a ferrite (FT240-32) to the USB cable with 15 rounds. Didn't help.
    3. Checking all antenna cables for shielding issues. Nope.
    4. Different computer and even running everthing on battery. Stays the same.

    Guys - I'm running out of ideas. Do you have any ideas left?


    (Picture of the "spiked" noisefloor when having WSJT-X active. USB+Ferrite attached)
  2. K8HIT

    K8HIT Premium Subscriber QRZ Page

    How about common grounds?
    1 person likes this.
  3. K8DO

    K8DO Ham Member QRZ Page

    Turn off power to the house.
    Run the 705 on internal battery.
    Any spikes?
    Turn on main breaker to house with ALL branch circuits Off and the internet cable unscrewed and disconnected from the router.
    Any spikes

    And so on. Power up things sequentially , one at a time, and you will find the source.
    Very likely a switching power supply in the ham shack or family computer, but could be a smoke detector, router, etc.
    K6GBW and K0UO like this.
  4. DM5TT

    DM5TT Ham Member QRZ Page

    Thanks for all replies

    @K8HIT: No changes in the noise level/behavior.

    @K8DO: Same behavior when running everything (IC705 and Notebook) on battery. All noise suddenly apperars when I connect it to the USB port.. I'm even able to see the USB data frames. When disconnecting it: everything is fine. Same behavior outside in the free field. Even tested with a second notebook.

    Guess I have to talk to my dealer and use the warranty. I was able to deal with USB issues in the past (some ferrit, some isolator and getting the ground done) but this time its crazy.
    Last edited: Nov 21, 2020
  5. K8HIT

    K8HIT Premium Subscriber QRZ Page

    Which dealer? Laptop, cable, transceiver, antenna

    Good luck tracking it down. For my IC-705 it was the external switching power supply. I also saw different noise levels on different bands as I swapped antennas.
    K0UO likes this.
  6. DM5TT

    DM5TT Ham Member QRZ Page


    I already tried changing my cable/antenna/laptop.

    Will call them on monday.
  7. K8HIT

    K8HIT Premium Subscriber QRZ Page

    How is that conversation going to go? My transceiver is picking up too much...

    All the other stuff is what shouldn't be emitting/interfering, but is. Is the cable acting like an antenna? Sounds like probably not since you tried ferrite (mix 31 I think). I don't know if any other mix would be worthwhile, several seem to cover VHF.

    Is it possible you are overdriving from the computer to the IC-705. Check your output on the computer and see if it's pegged. Control panel, sound, playback, USB Audio Codec (might be a preceding number). (added later in an edit, these don't affect receive, sorry)

    Page 8-13 in the basic manual talks about modulation levels. (added later in an edit, these don't affect receive, sorry)

    Do you have a 7300, 7610, or 9700 you can swap for the IC-705? To see what's going on with another rig.

    Maybe it's time to do a reset on the IC-705 and work from there.
    Last edited: Nov 21, 2020
  8. DM5TT

    DM5TT Ham Member QRZ Page

    Sorry. My behavior was not hamspirit-like.

    I think I came a small step closter to a solution: adding the FT240-32 ferrite to the antenna cable seems to reduce the USB-induced noise almost to zero.

    I will try to further analyze the source of this noise - as this is a behavior I'm not understanding yet in detail.

    Thanks for your tips regarding the IC-705!
  9. WA4SIX

    WA4SIX Ham Member QRZ Page

    A good quality USB3.0 cable may do better. I have had issues with cheap USB3.0 cables before & then spent the money & all was good. Belkin is what I ended up with.

    KC9QBY and K0UO like this.
  10. K8HIT

    K8HIT Premium Subscriber QRZ Page

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