Modifications for the ICOM - RogerK

push buttonswitch ^ ^| |____________________| |_____________________________| |___C IIIIIV| n. c. --^ _]|_____________________________________________________|mic plug shield standard mic jackfor ICOMORICOM mic plug tip to the middle ring of a standard mic jack. Carry the shield straight from the mic plug sleve to the standard micjack sleve. Now you can put a DC PPT in the standard mic jack and then put either a headset mic or the mic plug from theSigtronic intercom into the PPT mic jack. NOTE that if you plug a mic or the intercom mic plug into this it will key the ICOM.______________________________________| |___C IIIIIV| n. c. --^ _]|_____________________________________|mic plugstandard mic jackfor ICOMStandard aircraft radios use the tip to shield to key the transmitter, the ICOM does NOT use this method.David Clock PPT switch switches BOTH the mic lead AND the tx key lead, I think some others do as well.Jim Needham N201S------------------------------------------------------------------------When I wanted to do this, I started out by making two simple straight through adapters, one for the mic and one for the phone.Then I measured all combinations trying to figure out how ICOM did thier trick. I accidently shorted the mic tip to shield and thetx LCD lit. I also pluged a mic from a headset and noticed that the tx keyed, and having another radio on the bench, heard thefeedback.ICOM mic jack, only 2 conductortip to shield, about 4 or 5 voltsphone jackrx, audio from tip to shieldtx, same DC as above from tip to shieldMy installation does work. In the air, on the ground, upside down B-{)### I have also talked to someone else in my plane fromanother ICOM and it sonded good to me.Hope you have the same good luck that I have had. Stay out of the trees.Jim Needham N201SThis modification is read 804 times.top of page27-03-2000(IC-2GXAT) The ICOM 2GXAT HARDWARE MOD1. Open the radio by following the manuals instructions.2. On the half with the display and tone keys find the big chip (logic chip)3. To the right of it there are some small parts that look like this:|--------|| Logic | XX XX| Chip | x| |D14----> x XX| | x x|--------| XX XX XX