Icom A23 Wiring

[daveb]

Wiring a helmet with a stereo jack (mike & headphones) and a PPT for an IC –A23. These have just the one mini jack for connecting to the radio. I have the headphones & mike connected so that when using the PPT button on the radio I get sideband from the helmet mike and the red send light, it receives correctly through the headset so that’s wired OK.

I now have the external PPT with four terminals. Using this to short the tip from the headphones jack to ground gives me the headphones off and the red send light on the radio working. At this point I have no sideband when using this external PPT and not sure if the mike is working on send. I still have two wires from the switch and no luck to date putting them anywhere useful.

Appreciate your thoughts, this must be simple, but then with wiring, so am I!!

Dave

[PW_Plack]

Dave,

I don't have the wiring diagram for this radio, but Icom normally uses the mic lead and ground for both audio and PTT. To transmit, the PTT switch is used not to short the mic connector to ground, but to switch a resistor to ground. If you put the right value resistor in series with your PTT switch, and change the connection from the headphone pin to the mic pin, it should work.

I don't know the correct value of that resistor, but I'd go to Radio Shack and get a 5-pack of 1.2 K resistors. (They won't sell you just one, but a 5-pack is cheap.) Try connecting one across the mic pin, and see if that puts the radio in transmit. You should have working sidetone.

Don't ever just short these leads to ground! The output of the audio amplifier probably runs through a resistor to feed the headphones, but just shorting it out could still damage the audio chip.

I'm told Icom tech support will e-mail you a PDF with the wiring diagram for the OPC-967, the adapter you're supposed to buy to use an external aviation headset with the A23. It probably has the correct value for this resistor, and a schematic showing the correct points for PTT attachment.

Find a link for tech support at: Icom America (http://www.icomamerica.com/support/documents/cables.asp)

[daveb]

Thanks Paul,

While what you say is clear, translating that to which wire goes where is another thing. :o I have now tried shorting the mike to ground (and all the other possibilities) with resistors around 1.2K and can get the transmit light going but no sideband and presumably no voice transmit. I will contact Icom support next week, there is a local distributor in my city. I think may not have understood what you suggested on this wiring correctly.

Dave

BTW Thanks also for all your antenna posts - by lurking I think I have that one sorted now.

[Chopper Reid]

David Carson Electronics Mildura would be able to help you there as well. They do all sorts of helmet wiring with different radios. David does my helmet wiring for me .