I want to revive this old thread. I have a Shure 527B microphone. I'm trying to wire it to a 5 Pin plug for a Uniden Grant XL/Uniden Madison.
Unfortunately, I cannot get it to work. I get squeal upon transmit. I've tried the 4.7k ohm resistor on the audio line solution, and this only disables my transmit ability. Without the resistor, I get key plus feedback.
I've tried rewiring according to the drawing posted here, but I"m not quite sure it's correct. Squeal is still a problem.
I've contacted Shure, and followed the advice given. I've achieved the same result. Surely there must be someone out there using this microphone successfully with a 5 pin - or even a 4 pin?
Here's the response from Shure:
527B connected to Cobra radio
Response By Email (Michael P) (06/30/2016 03:19 PM)
Sorry, I do not have input on this. Cobra must be the source of the answer.
Inform Cobra that the 527B/577B can provide a dry contact closure; the closure is normally open when the mic signal is muted, and the closure is closed with the mic signal is active. Only Cobra knows how their radio will react.
If you wish to experiment, try Red wire to TX and Black wire to Common/Shield. This should work is the radio is normally in Rx mode.
Customer By Email (Bryne Last Name) (06/30/2016 03:03 PM)
Hi thanks for your response. TX is transmit, RX is receive & there's a key at the top
If the drawing.
RX and TX together upon PTT will cause the radio to squeal
I think.
I know these radios do not receive without a
Microphone plugged in. So, Receive needs to be "on"
When mic is plugged in, and "off" upon transmit.
Wouldn't this require a modification of the wiring to the switch itself?
Please advise - I'm hoping you might have some input on this.
Thanks for your help.
Bryne
N7BB
On Jun 30, 2016, at 11:15 AM, Shure Support <support@shure.com> wrote:
Response By Email (Michael P) (06/30/2016 01:15 PM)
For 527B/577B, the audio is the simple part:
Green wire to MODULATION pin
White wire to Common/Shield pin
Shield surrounding Green and White to Common/Shield pin
However, the RX and TX pins are ill-defined based on the drawing. So as a starting point:
Red wire to TX
Black wire to RX
When the 527B/577B mic button is depressed, the RX pin and the TX pin will be connected together. We hope this will put the radio in Transmit mode.
If not, please contact Cobra. The red wire and black wire are a simple dry contact closure.
I would appreciate any assistance from anyone who has wired this microphone to this transceiver correctly - even if it involves getting a different type of switch.
Thanks.