Wiring Color Code and Pinouts
Icom HM-103 Hand Mic.
Used on IC-703, IC-706 all models, IC-2000, IC-2000H
NOTE: View RJ-45 Connector with the locking catch away from
you and contacts up. This will orient pins as shown in diagram below.
lower diagram below
Pin 1- 8 VDC+
Red (May not be present. If so then N/C)
Pin 2- UP/DOWN Black
Pin 3- AF out N/C
Pin 4- PTT
Pin 5- Mic Gnd
Shield (Black #2)
Pin 6- Mic +
Pin 7- Ground
Pin 8- Squelch
See first diagram below.
The above diagram shows the color code and pin-out for CAT-5 connectors used in computer networking. Cross-reference
the HM-103 data to position the wires properly in the new RJ-45 connector.
Here is the RJ-45 in the same orientation as the regular CAT-5 plug, but with the color codes for the HM-103 Hand Mic.
Ignore the reference to "568B" under the bottom illustration. Note that three pins, 1, 3, and 8 may have no wires
present. The HM-103 only uses 2, 4, 5, 6, and 7. Pin 1 may have a red wire present in the RJ-45 but it is not used inside
the mic itself. Pin 5 (the second black in the color code) is where the shield gets attached. The supplier apparently
added a short wire "tail" to the shield to place it in the RJ-45. This wire was insulated with a black sheath. Do not
attempt to insert the shield directly into the RJ-45. I once purchased a mic from an overseas supplier who had done this and
within a few weeks the shield had shorted to the mic + pin next to it and I had to repair that connector all over again. Please
note, This color code may be different on your mic. I am led to believe that Icom used several different suppliers
for their mic cords. Not all had the same color code. Be sure to check your mic against this code and note any differences.
I was unable to position the illustration of the RJ-45 exactly where I wanted to, but
you get the idea. Pin 5 is where the shield goes, but you will probably have to solder a short length of wire to the shield
to get it to fit inside the RJ-45. Use a fine soldering tip and keep the joint small and smooth or it will not fit.
An alternative solution is to cut about 4" off the end of a CAT-5 jumper that already
has an RJ-45 installed on the end. Then using the color codes and pin positions shown above, splice each wire from the HM-103
to its matching wire in the CAT-5 cable pigtail. Reinforce the splice as necessary and plug it back into the radio. If
you have done the splicing correctly, it will work.
Please note, these instructions are (as usual) not guaranteed in any way. Perform this
work at your own risk. Any errors in wiring may cause significant damage to your rig.