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Author Topic: Icom Microphone pin connection question  (Read 624 times)
KU4UV
Member

Posts: 430




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« on: July 19, 2009, 06:10:48 AM »

Hello all.

I have an Icom 718 that I am using along with a soundcard interface that was purchased from a kit.  I am using a homebrew box that has a small toggle switch in it to manually key the radio.  I can't figure out how to key the radio using my laptop's serial port, so I decided to manually key the transmitter using a toggle switch until I can do some further testing to determine how to key the transmitte via the rts or buy a USB to serial interface to try that.  My laptop is an older Toshiba that doesn't even have a USB port, so I may be out of luck until I purchase a new laptop.  Anyway, my question regards the micropne pins on the 718 and other Icom transceivers.  These are pin 1 (Mic audio) and pin 7 (microphone ground).  Is there any danger to the transceiver if these two pins are accidentally shorted?  The reason I ask this is that I have two male phono plugs that I am using for both the microhone audio and the PTT.  I have heard that the Icom transceivers use phantom power on the mic line, and that you can damage the tranceiver if the mic and mic ground pins are shorted together.  Does anyone know if there is any danger to this?  Is a blocking capacitor need on my PTT switch to prevent damaging the transceiver in case the PTT is accidentally connected to the microphone male phono plug.  I am using a femal phono jack for the box that has the PTT toggle switch.  MNaybe this isn't the best way to go about doing this, but I didn't know if there was any danger in shorting pins 1 and 7 together.  Can anyone help me out on this one?  Thanks gang!

73,
Mike KU4UV
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KD8IIC
Member

Posts: 648




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« Reply #1 on: July 19, 2009, 07:51:02 AM »

Look up Icom Customer Service and e-mail them.Their tech staff is Super.You'll get an answer in 48 hrs.You can interact w/them well if still unclear.You know you have an acc.jack in the rear that has send,gnd. and other functions also.. Lane
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AA4PB
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Posts: 14339




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« Reply #2 on: July 19, 2009, 10:15:08 AM »

The bias voltage is fed through a resistor to the mike lead so you are not likely damage the radio by momentarily shorting it to ground (although I wouldn't recommend routinly doing this on purpose). The pin that can easily damage the radio if shorted is the 8V power pin on the mike connector.
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Bob  AA4PB
Garrisonville, VA
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