There are three basic types of
dynamic microphones, (A) relay switching, (B) electronic switching, (C) special electronic
switching. If the old mic. is available, figuring out the wiring code is just a
matter of trial and error. Lets look at Figure (A) the relay switching mic.
Using an ohmmeter it is possible to find the mic. element wires B, C by pressing the mic.
key, the meter will read about 500+ ohms. some mics. might read higher, don't worry
test, it may be OK. The next wires to find are A & D, these switch the
transmitter on. It will read open until the key is pressed, then ohms will read
In figure (B) electronic switching
the ohm meter reads open on wires A, D and shorted wires A, B. A, B usually grounds
the speaker for audio, but when key is pressed for transmit, the speaker goes off or A, B
opens and A, D is shorted, to turn transmitter on. Now note A, C is open until mic.
key is pressed, then ohms read 500+ or more for mic. audio.
The most involved mic. is the special
mic. Figure (C). The main wiring is the same a Fig. (B), but there is another set of
wires D, E, F. Usually this set is used to switch voltages from receiver to
transmitter. Voltage is on wire E, then E, D will supply voltage to receiver.
When key is pressed E switches to F and supplies voltage to the transmitter. Using
an ohmmeter it is possible to see the opening and closing of this switch.