You should look for Icom model HM-7 HM-10 or SM-5. Occasionally
available on ebay and the news groups. Seen prices range from $10-15 up
to about $50. You can check Icoms web site. They have a mic and radio
compatibility chart.

Michael Brown wrote:
I recently purchased an Icom 720A on eBay, but the radio is missing the
microphone. I understand that the early model of Icom transceivers had a
preamp in the microphone itself, and you have to have either the original
mic that came with the radio, or a similar microphone with a preamp to drive
the audio in the transceiver. Does anyone know of a source or web page that
has microphones for older Icom transceiver like the 720A? I'm not sure if
Heil offers a mic for the 720A or not, but the issue of the older Icom mics
is listed on their site. Can anyone help me out on this one? Just send me
an e-mail if you have any suggestions. Thanks!

73,
Mike KU4UV
Lexington, KY.