> The reason you want to unplug the mike is that when you > ARE transmitting with any soundcard mode via the ACC > connector, the mike will be LIVE - all room noise will be > transmitted at the same time as your data transmission. > 73, Bob, KD7NM Hi Bob,
There are other rigs that have the same issue. I encountered this problem on an Icom IC-718. When the rear ACC port is used for audio and PTT, the microphone is "live". Most ops using this rig simply disconnect the microphone while operating digital modes. That is cumbersome and eventually wears out the microphone connector. The philosophy of the application I'm using (ALE) is not only to use digital data/text mode, but also SSB selective calling and responding immediately to an ALE call with SSB voice. So, I modified the Icom HM-36 stock hand microphone. Inside the HM-36 hand mic, the PTT switch is single pole double throw (SPDT). The Common pin of the switch is ground. The Normally Open is PTT. The Normally Closed is connected to the Mic Up/Down switches (so they are inactive during PTT). I cut the line to the Up/Down switches and soldered it directly to the mic ground. Then, I soldered an additional wire to the microphone element +hot ; and the other end of the wire to the Normally Closed pin of the PTT switch (where the Up/Down switches had originally been connected). This shorts the microphone element to ground whenever the microphone PTT button is not pushed. The result is, the microphone is muted, when the ACC rear panel PTT is in use... and the microphone functions normally when the mic button is pressed. 73 Bonnie VR2/KQ6XA
