Paid for an Icom IC-SM6. Guy sent me an SM-2.

Discussion in 'Microphones, Speakers & Audio Processing' started by KE0EYJ, Jul 21, 2017.

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  1. KE0EYJ

    KE0EYJ XML Subscriber QRZ Page

    This happened in Korea, and I'm trying to get my money back.

    This guy sold me what he said was an SM-6 mic. I plugged it into my Icom 7300, and I get huge RF feedback (I have no problems with any other mics and this radio). So I checked, and the bottom of the mic clearly shows it's an old SM-2. There is a connector on it that fits my 7300, but it's not working right. I am trying to get my money back, but the guy keeps trying to tell me that the SM-2 is the same as the SM-6, only the SM-6 has the 8-pin connector. Apparently he thinks just having the 8-pin connector magically makes it an SM-6 despite what's on the bottom.

    He says he will send my money back, but in case he tries to come up with more sob crap about an SM-2 being the same thing, what is different, internally, that would make the SM-2 feed back horribly on my 7300? It sounds like lots of RF feedback. When I key the mic, I hear the room noise, but as soon as I talk, I get the RF.

    If he ends up not sending me money, are there any changes I can make that will remove the RF issue?

    Not happy. I paid for an SM-6. His photos included an SM-6 manual. He even sent me an SM-6 manual with it.
  2. K5RT

    K5RT Ham Member QRZ Page

    How do you know it's an RF issue and not a wiring issue?
  3. KE0EYJ

    KE0EYJ XML Subscriber QRZ Page

    I've heard RF problems before (other radio) and it sounds like that. When I key it down, I can hear room noise just fine, but as soon as I speak, I get distorted audio. Just a guess, really.

    My Korean friend tells me there have been some counterfeit Chinese Icom products, over the years, including mics. Could very well be that problem, too.

    In any case, he's apparently sent money transferred back to my bank account for it. I'll check Monday, and then send him the mic back. I haven't properly set-up internet banking to check (it's all in Korean, and rather difficult for me, given the digital certificates required).
  4. N7EKU

    N7EKU Ham Member QRZ Page


    According the the universal radio site, the IC-2 came from Icom wired either with their early 4pin plug, or their newer 8pin plug. I would think the mic would be fine for your newer rig if it was wired correctly. Try this: SM-6 Desktop microphone wiring.pdf

    Also, you might check the level setting on the bottom of the mic -- maybe it is turned up way too high?


  5. KA9JLM

    KA9JLM Ham Member QRZ Page

    Your link did not work for me.

    That control may work just the opposite of expected.
  6. KE0EYJ

    KE0EYJ XML Subscriber QRZ Page

    Tried that.

    It's either wired wrong, or who knows.

    Thanks for the comments. He sent me the money back, apparently, so not planning to open it up. Will just return it, and buy something else.

    Link didn't work, either.
  7. N7EKU

    N7EKU Ham Member QRZ Page

    Crazy long link didn't copy/paste correctly :p

    Well just search for the PDF and it will be found directly.


  8. W9GB

    W9GB Ham Member QRZ Page

    The main issue with the earlier SM-2 ... how is the Elecret element powered?
    Martin, K7MEM answered this query (SM-2) in May 2013.

    IMG_4316.JPG IMG_4317.JPG
    The SM-2 and SM-6 models have an adjustment for Low to High on the bottom of the microphone base. The SM-6 mic is powered from the Icom transceiver (specific pin with +8 VDC, 50 mA), has a built-in pre-amp. The SM-2 pre-amplifier schematic (above).

    Icom SM-6 manual (Icom Global Support, Japan), circa 1989 (attached).
    This includes the pre-amp schematic within the microphone base.

    Attached Files:

    Last edited: Jul 22, 2017
  9. KM3F

    KM3F Ham Member QRZ Page

    On SSB when you key up and hear room noise, the power output of the radio is >>>>>low.
    Once you talk and cause the radio to make (a lot) of output, it feeds back to its self through the mike as a loop action until you unkey.
    Is that hard to understand?
    The mike would have worked if wired correctly.
    The seller really was not wrong about it but assumed you could handle it.
    This is what happens when you have no background in electronics.
    Little things become a hassle.
    Good luck.
  10. KE0EYJ

    KE0EYJ XML Subscriber QRZ Page

    K3MF, don't be silly.

    If you are going to post in my thread, please stop the trolling remarks, like, "the seller thought you could handle it" and swipes at me for not "having a background in electronics."

    No call for this kind of asshattedness.

    He labeled it an SM-6 in the ad. He included an SM-6 manual. The mic he actually sent is an SM-2, and clearly says so, on the bottom.

    Actually, it was mentioned on the Icom board that the original sm-2 outputs a higher level than the 7300 is capable of handling, and creates feedback. How it goes about this, I do not know. It probably has something to do with it being a different mic, entirely?

    The sm-2 is not compatible with the 7300. Why should I be expected to rewire a mic sold to me as an SM-6, which arrived to be an SM-2?

    Is that question hard to understand?

    Now, go take some Geritol and stop trolling my thread, please.

    Last edited: Jul 22, 2017
    W1PEP, WG7X, K7GLD and 1 other person like this.

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