4-wire mike.
5-pin mike socket.
Math problem. 5 doesn't equal 4.
The 5-pin mike socket has two separate ground pins. One for the audio only, and one for the transmit/receive switching circuit only.
Each ground pin is separate to prevent feedback into the mike amplifier.
4-wire mike has only one ground, the shield braid.
You have three options.
1) Tie pins 2 and 4 together inside the mike plug, and hook the shield braid to that.
2) Connect the braid to pin 4 only.
3) Connect the braid to pin 2 only.
One of these tends to cause feedback squeal on transmit.
The other one will cause a feedback howl in the receiver audio, mostly in sideband modes.
The other one gets you feedback issues in both transmit and receive.
Turner introduced the "+3B" model when this kind of radio appeared in the late 70s. Has six wires in the cord so you can also use it with Johnson radios. The shield conductor is separate from the T/R switch common wire. Also has an added switch circuit that unhooks the audio wire from the preamp in receive. This stops the "deafening squeal in receive" problem may 23-channel AM-only radios would have when connected to a 4-wire power mike.
Turner sold an "upgrade" kit for those mike. It included additional leaf contacts and screws to add the switch circuits needed. The 5-wire or 6-wire cord was extra.
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