The Radio Information Board

i have another company dtmf microphone and want to wire it to the tk805d radio , does someone out there have the pinouts and what is designated for each pin of the 6 pin rj45 modular connector ? Please send .....

Okay, here goes:

Take the modular mic connector, face the tab down and look at it with the pins facing you. From right to left:

1 SB (Switched 12V) (Right most pin)
2 PTT GROUND
3 PTT
4 MIC GND
5 MIC HI
6 HOOKSWITCH (Left most pin)

Remember, this is the microphone side. The radio side will be reversed.

input ? or what value would you think would be good to get down to 8 volts to feed near correct voltage ...? the microphone i plan to use is a johnson 16 tone dtmf type (pn#589-7600-022) nice new mike , has a 8 pin on now - but wont for long......
also will need to wire another johnson mike to the same radio (tk805d) other johnson mike is a 12 button keypad dtmf (250-0751-021) looks just like the CES 600L style....scott Is it better you think ? to use a resistor or 8 volt zener ? scott

Well, you could certainly use a dropping resistor, providing that you know how much current the DTMF pad draws. You could also use a 78L08 voltage regulator (it's a 3 pin job in a small transistor case), or you could do the zener thing too. If it were me, I think I'd go for the voltage regulator.

Also, Kenwood radios (and many other manufacturers) usually put 8 volts or so on the MIC HI pin to give the electret microphone element some bias. Make sure the Johnson microphones have electret elements and not dynamic ones. If they are dynamic mics (unlikely, but possible), you'll have to add a blocking capacitor to keep the DC out of the mic coil.

Unfortunately, you couldn't run the DTMF pad off the mic bias...not enough current there.

thank you again for your time also scott

I know these messages are over a year old, but the mic in question (589-7600-022) is actually a re-labeled Icom HM-100T, even though it says EF Johnson and Product of Transcrypt on it. I use it (the EF Johnson one) on my Icom IC-2100H.