Hi,
There is a problem with the IC7000 DSP processing in the audio chain if you set the TX audio bandwidth too narrow. Leave the TX DSP set on maximum bandwidth.
Some voice characteristics and microphone responses just don't suit the radio. I think this is because ICOM chose to remove the equalisation functionality from the IC7000 so that it wasn't comparable to the Pro III.
Almost any electret insert will work, but those with a 'Telephone' or 'Noise cancelling' characteristic from 300Hz to 5 or 6KHz seem to behave the best.
You can usually trigger DSP 'ringing' by making a 'clicking' noise into the microphone with your tongue and the roof of your mouth. Listen on another radio and choose a microphone which produces the least DSP artifacts.
Regards,
Martin - G8JNJ
www.g8jnj.webs.com