hmn4060B Mod help

[ki4ccz]

I was wondering if any of you guys had a pinout of the mic connector of a hmn4060B desktop mic. Want to, IF it will work, hook it up to my IC-V8000. I call the net and the audio from this mic would be great.

[ki4ccz]

I have figured out how to get it to key the radio but I cannot get any audio thru the mic. Help Please!!!!
Using
http://batlabs.com/images/gm300mic.gif
and
http://homepage.ntlworld.com/rg4wpw/hm133.html

[k2hz]

Motorla mics are electret type and require a bias voltage for the mic element and/or internal circuits. They are not compatible with most ham radios that use a 600 ohm dynamic mic.

[ki4ccz]

IS there any way to create that circuit. I have this mic hooked into a RJ45 Port and breadboard to figure out what pins go where. SO any suggestions to make it work? Up to trying most anything.
Jeremy

[Will]

The mic circuit in all Motorola mobile mics, including Maxtrac, Radius, CDM, GM, ect, require mic bias. Some have dynamic elements, others have an electret element, and an amplifier circuit. These mics typically have an output of 80 to 120 milivolts.

For your application you can try using a 600 ohm resistor from the 8 volt pin on the IC-V8000, to microphone hi for the bias. Then a coupling capacitor from the microphone hi to the IC-V8000 radio's mic input.

[ki4ccz]

Does it matter what value Cap?

[Will]

The value of the coupling cap is not really critical. .1uf would be a good start, you can increase the value to get more bassey response or decrease the value to get more highs. The value depends on the input of the IC-8000 Mic input circuit impedance.

[ki4ccz]

Still no luck.
Here is what I have done so far.
Icom Side TO Moto Side
8V thru 680 Ohm resistor to Mic Audio
PTT to PTT
10 MFD Cap on mic to mic audio
Mic ground to ground
PTT ground to Hook.


Still no audio thru the radio. Is 680 ohm too much resistance?
Jeremy

[Bigred]

680 ohm resistor might be loading the mic hi line. I've biased mot mics with as high as several Kohms. Increase the resistor while at least providing 5 or 6 volts to the mic hi line.