I am new to collecting vintage Collins gear, and have a question: How should I wire up a Turner Lmm-8 mobile mike to my KWM 2? The Turner has four (4) wires - red, black, green, and white - but the Collins mike connector only has three (3) connections, a tip, ring, and sleve?
Thanks for reading!
PAUL
WA6RXM
Collins KWM 2 microphone.
The KWM2's cute little nonstandard mic plug is wired thus:
Tip - PTT
Ring - Mic Audio
Sleeve - Ground (Common)
Note that Tip and Ring are exactly backwards from what anyone would expect. That's Collins. The engineers wired it that way so that a mic element doesn't get connected across the substantial current of the keying circuit should someone plug or unplug with power on.
Also Note Carefully: I've encountered a few KWM's where someone had replaced the jack and wired the Tip and Ring the other way round. Good idea to take your plug with the barrel off of it, plug it into the mic jack and temporarily short Tip to Sleeve and make sure the radio switches. Might be wired backwards, in which case Ring to Sleeve will key the relay. If you have one of these, very good idea to open the rig and make it right because of that keying current mic damage situation!
Shorting Tip to Sleeve (PTT switch) puts the transceiver into Transmit mode fi the radio is still boxstock.
Can't tell you about that Turner mic, but you can trace the PTT easily with an ohmmeter, continuity tester or even a bulb and battery.
Typically I'd expect the mic to be wired thus when signal wire color code is used as here:
RED - PTT switch
BLK -- other side of PTT switch
WHT - Mic Audio (+)
GRN - Mic Common (-)
But don't count on that with any used mic, use that ohmeter to prove the two PTT wires and then you will know the other two have to be the Mic.
Wiring is simple enough once you find that out, the BLK and GRN go to the Sleeve of the KWM plug.
Red to Tip
White to Ring
73,
Tip - PTT
Ring - Mic Audio
Sleeve - Ground (Common)
Note that Tip and Ring are exactly backwards from what anyone would expect. That's Collins. The engineers wired it that way so that a mic element doesn't get connected across the substantial current of the keying circuit should someone plug or unplug with power on.
Also Note Carefully: I've encountered a few KWM's where someone had replaced the jack and wired the Tip and Ring the other way round. Good idea to take your plug with the barrel off of it, plug it into the mic jack and temporarily short Tip to Sleeve and make sure the radio switches. Might be wired backwards, in which case Ring to Sleeve will key the relay. If you have one of these, very good idea to open the rig and make it right because of that keying current mic damage situation!
Shorting Tip to Sleeve (PTT switch) puts the transceiver into Transmit mode fi the radio is still boxstock.
Can't tell you about that Turner mic, but you can trace the PTT easily with an ohmmeter, continuity tester or even a bulb and battery.
Typically I'd expect the mic to be wired thus when signal wire color code is used as here:
RED - PTT switch
BLK -- other side of PTT switch
WHT - Mic Audio (+)
GRN - Mic Common (-)
But don't count on that with any used mic, use that ohmeter to prove the two PTT wires and then you will know the other two have to be the Mic.
Wiring is simple enough once you find that out, the BLK and GRN go to the Sleeve of the KWM plug.
Red to Tip
White to Ring
73,