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Thread: Bad Audio Transmit on Icom 2720

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  1. #1

    Default

    I just purchased a used Icom 2720 from one of those ham trade equipment boards. #This is my second 2720. #My first 2720 is first rate! #No problems! #This second 2720 exhibits the following:

    -it has good RF power output at antenna (as judged by other hams on the local repeater)
    -it is full quieting into the repeater

    -the audio volume is exceptionally low. #this is a problem. #bad audio amp in the radio?
    -this audio problem exists even when I trade out microphones from my good Icom unit

    -I am using an Astron VS-35 power supply
    -When attempting to transmit full power (35 W) on 70cm, the system instantly trips the household circuit breaker

    What is the problem? #How do I fix it?
    Thanks,
    John
    KE5IRN

  2. #2
    Join Date
    Mar 2001
    Location
    north west wisconsin
    Posts
    970

    Default

    How does your tone signal gget to the repeater.
    If tone level is ok and not distorted, then likely the first audio amp
    as I think the tone is inserted after the first amp.
    I didnt look at my schematic recently.

  3. #3

    Default

    Quote Originally Posted by [b
    Quote[/b] (ke5irn @ Jan. 23 2008,21:08)]...
    -the audio volume is exceptionally low. #this is a problem.
    ...
    -When attempting to transmit full power (35 W) on 70cm, the system instantly trips the household circuit breaker

    What is the problem? #How do I fix it?
    Thanks,
    John
    KE5IRN
    Do you have a 0.3A circuit breaker in your house???

    I can't think of anything that would cause the breaker-tripping problem other than 70cm RF getting into your house wiring (there's no 35W option on 2M). That's definitely something I'd fix before worrying about the audio, if the audio problem isn't just a matter of setting a menu option.

    The 2720H has both Wide (5KHz) and Narrow (2.8KHz) deviation capabilities. Go into the SET menu and check that Wide FM ("OF") is selected (left band only).

    The mic gain is set during power up. Hold SET and push POWER for 1 sec. Go to the mic gain menu and make sure the mic gain is set to high "H".

    Also, the 2720 has had issues with RF getting into the mic. Take a look at mods.dk to address this and other 2720 issues.

    Hope this is helpful.
    73, Dave

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