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Thread: IC-718 Transmitted sound very distorded

  1. #1

    Default IC-718 Transmitted sound very distorded

    I own a ICOM IC-178 transceiver powered with a 12V battery. It drives a Hustler 6BTV antenna located at 100 feets from the house. The station is at 15 feets from the ground in a second floor room. The SWR from the station has been tested and less that 1.5.
    Using the ICOM mic that comes with the transceiver, and listening with a TECSUN radio in SSB mode, the transmitted sound is very distorded at any MIC gain and RF power. What could be the cause ?

  2. #2
    Super Moderator 5B4AJB's Avatar
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    Well, a typical car battery will comfortably run it on full power for about half an hour, longer if the SWR is low.

    Is it possible to make an adaptor for the microphone and plug it into a PC or HiFi to hear the audio quality before it goes into the radio?

    Could be there's just too much mic gain, check the ALC on the radio is not going crazy when you transmit (it shouldn't move much).

  3. #3

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    Quote Originally Posted by marc.ouellet View Post
    I own a ICOM IC-178 transceiver powered with a 12V battery. It drives a Hustler 6BTV antenna located at 100 feets from the house. The station is at 15 feets from the ground in a second floor room. The SWR from the station has been tested and less that 1.5.
    Using the ICOM mic that comes with the transceiver, and listening with a TECSUN radio in SSB mode, the transmitted sound is very distorded at any MIC gain and RF power. What could be the cause ?
    Quote Originally Posted by 5B4AJB View Post
    Well, a typical car battery will comfortably run it on full power for about half an hour, longer if the SWR is low.

    Is it possible to make an adaptor for the microphone and plug it into a PC or HiFi to hear the audio quality before it goes into the radio?

    Could be there's just too much mic gain, check the ALC on the radio is not going crazy when you transmit (it shouldn't move much).
    I already played with the mic gain and ALC, but got no improvement. I suspect the mic so I would like to make an adapter to test to mic with a PC. Where can I find a an example of doing it ?

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    Super Moderator 5B4AJB's Avatar
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    Page 12 of the manual shows pins 1 & 7 are used for the microphone circuit.

    For example:-
    An old pair of headphones you can chop up would be easy to connect to a P.C.
    Cut the wire near the speaker end of the headphones.
    Strip both the inner and outer conductors from one of the speaker wires, leaving the other one unused.
    Insert a wire into either side of the the notch, (closest to the notch) on the Icom microphone.
    Plug into microphone input on computer, hit software record and sing away (you might have to hold the PTT button).

    If it doesn't work, swap the wires around or use the other speaker wire.

    Some things to note while recording are distance & angle of microphone...

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    My guess is trying to run a radio at 100 watts output, off a 12v battery IS the problem. Icoms love full voltage and current available and running at less is asking for trouble.

    Try turning down the power output and test again. It should clean up unless the available voltage is too low. Then maybe some charging is in order.

  6. #6

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    How close is the receiver antenna to the transmitter antenna? Sounds like you're trying to hear yourself 100w strong on a receiver that is right next to the transmitter. That would be very very mean to the receiver.

    Even as little as 12w on the Sirio827 overloads the receiver i have listening on my other antenna.
    Last edited by brandon lind; Fri 13th Dec 2019 at 16:06.

  7. #7

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    Quote Originally Posted by marc.ouellet View Post
    I own a ICOM IC-178 transceiver powered with a 12V battery. It drives a Hustler 6BTV antenna located at 100 feets from the house. The station is at 15 feets from the ground in a second floor room. The SWR from the station has been tested and less that 1.5.
    Using the ICOM mic that comes with the transceiver, and listening with a TECSUN radio in SSB mode, the transmitted sound is very distorded at any MIC gain and RF power. What could be the cause ?
    You're overloading the front end of the TECSUN radio?

  8. #8
    Super Moderator 5B4AJB's Avatar
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    yeah, could be those things too, might be worth putting a ferrite on the power leads too if the antenna is very close...

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