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ICOM ic-910h

Discussion in 'Ham Equipment' started by nite-eagle, Jun 25, 2005.

  1. nite-eagle

    nite-eagle LIFE IS TO SHORT FOR QRP!

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    Hello everyone, I bought a used ic910h and am having a problem with it so thought I would ask if anyone else had the same problem. When transmitting on FM or SSB the audio sounds very good but there is a hum sound in the back ground. I have been told it sounds almost like a 60hz hum. The audio is great but the noise/hum sound is always in the back ground. It has the DSP in the two meter side but the noise the there if the DSP is on or off. I have tried two different power supplies with the same result. I went through the menu settings and cant get rid of this noise. Any one have an idea? Thanks in advance for your help. 73 and God Bless, John KB9RYI


     

  2. bandaid kid

    bandaid kid Active Member

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    Need more info. Is this noise in your reception or is it in your transmitted signal? Are you using a power supply or battery? What sort of mic are you using?
     
  3. nite-eagle

    nite-eagle LIFE IS TO SHORT FOR QRP!

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    ICOM in-910h

    The noise is on the transmitted signal. I dont hear it on receive at all. I started out using a Pyramid 25-amp power supply. I then changed to an Astron 35-amp power supply. The same with both supplies. I am using the stock hand mic. I am using a Diamond X510 dual band vertical antenna. I have a Diamond duplexer to combine the VHF and UHF from the radio to the antenna. I did try it without the duplexer with the same noise on the transmitted signal. As I said above I dont hear it on the receive audio at all. Thanks for your reply.
     
  4. Happy_Hamer

    Happy_Hamer Administrator
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    I would almost say that on FM you may have a PL Tone set that does not need to be?

    I was talking on FM simplex and was told there was a hum in my transmitted signal, I was checking power supply, mic connection, antenna connections, SWR and finally looked at the display to see I accidently had a tone on. Shut the tone off and all was good. I have also programmed a PL tone on a repeater that did not need one, it was listed in the book as needing one but the owner disabled it for one reason or another and no tone was needed.

    BUT since you say it happens on SSB I would say that the tone has nothing to do with it, except for the fact that sometimes people "hear a hum" when they know you are having a problem but the hum is not there and they think they hear it?

    Try and see
     
  5. Moleculo

    Moleculo Administrator
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    How close is the radio to the power supply? I've had this happen to me when I had radio and power supply right next to each other, or radio on top of power supply.

    Also, here's another situation that may be helpful:

    There is a local that I talk on 2M FM to several times a week. One night he developed a really bad hum in his TX audio. He couldn't figure out what it was. I started trying to help him troubleshoot it. First thing I told him was turn of his computer notebook that's near his radios. As soon as he shut it off, the hum went away cables and components hooked up to the notebook: monitor, printer, scanner, etc. What finally fixed the problem was that he pulled the 2 pring power plug on the notebook and plugged it in the other way (turned the connector around). The noise went away. For some reason, when the plug was oriented one way, the notebook transformer was generating RF on the line. I've never seen that happen before, but I learned something new that night.
     
  6. Captain Kilowatt

    Captain Kilowatt Professional Amateur
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    Computer monitors are realy bad for that.I wish i had a dollar for every time I had to tell the office girls not to put the VHF desk mic next to their computer monitors.We have a base setup with multiple control heads as well as three remote offices in other towns.When they key up all you hear is HUUUUMMMMMMMMM! and a teensy bit of speech.Then they complain that the radio has a problem. :evil:
     
  7. bandaid kid

    bandaid kid Active Member

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    Nite Eagle,

    Do you have your radios and power supplies grounded to a good earth ground? An 8 foot grounding rod driven into the gound near the shack might be the answer if you don't have a ground. I have everything in the shack with a ground connection attatched to a short length of copper water pipe that uses copper braid to link with an ousdide ground rod. You can use the sheild from coax cable as a braid. You may be able to get away with just using your house electrical ground although a seperate ground rod is best.

    I'm thinking you may have a ground loop causing the hum and if you use Mole's suggestion and move the radio from the power supply and the hum is still there, you'll need to ground everything.

    From a safety issue, everything should be grounded anyhow. Radios, antennas, meters, amps, etc should be connected to ground rods and antennas should have lightning supressors running to ground rods.

    73
     
  8. BlueMR2

    BlueMR2 New Member

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    Did you ever get it figured out? My IC-910H has suddenly started doing the same thing (clean signal one day, loud "sounds like" 60 hz hum the next day on transmitted audio). Receive is perfectly clean. I've ruled out the antenna, cabling, power supply, and ground already. I've only tested on FM so far and have not tried using the digital interface instead of the hand mic, so still need to do those (plus SSB). Unlikely to be local interference as my IC-7000 in the same location does not have the same issue (and my prior experience is that the 7000 is significantly more susceptible to interference than the 910H).
     
  9. Captain Kilowatt

    Captain Kilowatt Professional Amateur
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    Man I hope he got it figured out by now. The last post in this thread was over 12 years ago. LOL
     
  10. BlueMR2

    BlueMR2 New Member

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    Yeah, I'm hoping he's still around and remembers! It'd be nice to start with known prior issues before having to examine *everything*!
     
  11. BlueMR2

    BlueMR2 New Member

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    For others that may have the same issue in the future and arrive here via Google (like I did). I was able to consistently duplicate the problem without any change on voice while changing antennas, grounds, power supplies, etc. I finally setup a digital link (with mic totally removed) and then there was no hum. So I reseated the mic and the problem appears to be gone. For now... Mic had not been removed in years and was still solidly connected so I'm not convinced that reseating it was a solution. Time will tell.
     

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