Pondering microphone connection options

Starting to ponder ways to connect the desk mic (an Astatic 877L) we picked up last month to the radio. Right now the mic has an XLR female connector on the end, while the radio uses an RJ-45 modular connector for the microphone input. I figure I have a few options:

  • Replace the existing cord on the microphone with some Cat5 that already has an RJ-45 connector on one end.
  • Make a pig tail with an XLR male connector and some Cat5 with an RJ-45 connector
  • Cut the XLR connector off and splice on a length of Cat5 with an RJ-45 connector

Fortunately, the bottom of the microphone has this handy wiring label. There aren’t very many wires to connect up to the radio.

Astatic 877L wiring diagram
Astatic 877L wiring diagram

Having a look inside the base of the microphone, everything looks to be wired up as shown on the label. It looks like if I choose to replace the cable with a length of Cat5, it will be a little bit of work, but shouldn’t be too bad.

Wiring inside the microphone base
Wiring inside the microphone base

From the Kenwood TS-480 manual, the pin-out for the microphone connector is

  • 1 – UP
  • 2 – +8V
  • 3 – GND
  • 4 – PTT
  • 5 – MIC GND
  • 6 – MIC
  • 7 – N/C
  • 8 – DOWN

Looks like red (XLR pin 2) would go to PTT (4) and black (XLR pin 3) I think would go to MIC GND (5). Not sure where the white wire should be connected to, but it currently goes to pin 1 on the XLR connector. The green wire in the mic doesn’t appear to be connected to anything.

The downside to replacing the mic cable with Cat5 is that the wires are quite a bit thinner, so I”ll have to give extra thought to strain relief at the microphone base.

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