Icom IC-2720h trouble

[airboss20]

I have an Icom IC-2720h that has been a solid radio for me for 7 years. I have had no trouble until a couple weeks ago. Now when I key the HM-133 microphone I only transmit a carrier with a ticking sound audible on another radio. However, when I replace the HM-133 mic with a HM-110 I am able to transmit voice normally. The issue with the HM-110 is that it is DTMF only, and has no radio function control. I ordered a new HM-133, thinking that the mic was bad, but the new HM-133 does the same thing as the old one. I never lost function control with the HM-133, only audio.

Has anyone else had this issue, or have any ideas on how to resolve it?

 

[fineshot1]

The HM133 and HM98 icom mics are actually data mics - that is to say that actually
pushing the ptt switch is not what keys the radio. When you push the ptt sw the mic
sends a data code to the radio to key up and when you let off the ptt sw another code
is sent by the mic to the radio to un-key. That's the simple explanation, its actually a
lot more complicated than that but the radio is backwards compatible with the older
conventional mics and that is why the HM110 worked.

It sounds like the radio might have an internal problem with the icom mic data
interface protocal and perhaps the radio and original mic should be sent back to
icom for troubleshooting and repair - just a suggestion as it seems like this one
may be a bit more than you( or I ) can handle.

I have done some minor research on these mics, perhaps it may help you or
perhaps not but see the links below. Good luck and please post back if you
get this resolved.


HM-133 Microphone PTT Issues

http://forum.ih8mud.com/electronic-toys/135044-anyone-using-icom-ic-208h-2m.html

Icom HM-98/HM-133 Internals - Wiki

 

[W2NJS]

Icom mic replacement?

HM133 mics have come 'way down in price on eBay in the last couple of years. You can get a 133,
or substitute a 118TN, or a 154 and do almost the same job as a 133. You might also consider replacing
the condenser mic element in your old 133 with a new element. Working on the insides of these units is
not difficult.

 

[airboss20]

I have purchased a new HM-133 Mic, unfortunately, it performs no better than the old one. Both of my HM-133s stiff function as controllers, I just can't speak through them.

 

[klyball]

I am having the same problem with a ic-2200h, i was wondering if and how you resolved the issue?

Thanks

 

[liftedtacoma4x]

IC-2200H Mic Output Modification

KB2LJJ Radio Mods Database and Manuals

 

[klyball]

Solved

I am having the same problem with a ic-2200h, i was wondering if and how you resolved the issue?

Thanks

found the problem on logic board a small inductor ep4 was disloged it was the mike ground line, all is well now