Superstar / Workman DM452
Wiring and modications
The Superstar DM452 microphone has a built in audio preamplifier with echo and reverb functions.
There is provisions internal to the microphone that controls the level of audio amplification and for echo. These controls are known as VR1 and VR2.
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Futher more there have been reports of squeal due to RF feedback getting back into the audio amplifier when mic gain is set high, this is due to poor grounding from the factory.
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So first we will look at a very simple way to fix this manufacturing defect.
You will notice that this shield is not grounded to the main circuit board.
You will notice i have installed a ring crimp and wired this so that is soldered to a nearby ground.
With this modification done, there is no longer any squeal from the microphone in transmit.
What is the wiring code?
How do i know which wire does what?
How do i wire this to my radio?
To first know how to wire to microphone to any radio, first we need to understand the microphone itself, how the PTT switch functions and how this switches various signals.
The image above is the diagram of how the contacts inside the switch works, as you can see this switch is broken down into 4 individual sections with 4 separate set of contacts.
The colors on this DM452 are the following:
(1) Black - Receive = Which is shorted to common ground thru white wire
(2) White - Common = Common to both Receive and Transmit
(3) Red - PTT = Which is shorted to common ground thru white wire
(4) Yellow - Microphone audio line +
(5) Shield - Microphone audio ground +
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To set the two variable controls in the back of the mic for a nice clear sound.
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1. Turn the echo control all the way down (left).
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2. For the volume you turn it all the off (left) then just barely turn it enough so that your radio modulates. You only turn it up (to the right) about 1mm. It's a very slight amount. Any more will make it over modulate, squeal and pick up a lot of background noise.
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3. Set the slide control on the front at about 1/4 to 1/2.
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If you use talkback you may need to turn the mic gain on your radio down a bit also to keep from getting feedback.
Above is the wire color code for use with the Cobra 200gtl DX
Notice that the Shield and White wire are connected together.
I hope with the information i have provided on this webpage, that this will help you wire your microphone to your next radio. Don't forget to add the new ground, your radio will thank you for it!
I would like to give a special thank you to my friend Darrell Peckham for the help with the wiring for the Superstar DM452 echo microphone... Thanks Darrell!