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Author Topic: Shure 450 series II mic to Drake TR7A  (Read 3907 times)
KEVIN1218
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Posts: 19




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« on: February 25, 2013, 12:37:08 PM »

Hello everyone,

I need help, please. No, mentally I am fine but my microphone wiring needs help!
Shure 450 Series II
Drake TR7A

I wired the Shure 450 series II microphone
Green wire to Pin #1
White wire to Pin #2
Ground wire to Pin #3
Pin #4 is empty

Unused microphone wires are the Black & Red.

The PTT switch does not activate Transceiver, nothing.

Did I fumble on the wiring? Please be specific with what color mic wire goes to what pin # of transceiver (4) pin connector

http://www.shure.com/americas/products/microphones/other/450-series-ii-voice-communication-microphone

http://www.wb4hfn.com/DRAKE/DrakeArticles/InsideTheTR7/Inside_The_TR7-03.htm

73's
Kevin
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K8AC
Member

Posts: 1478




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« Reply #1 on: February 25, 2013, 02:02:52 PM »

BLACK, WHITE and shield to Pin 3
Green to pin 1
Red to pin 2

The PTT switch wiring is rather odd.  To transmit, you must ground pin 2 on the TR7 mic connector.  That's what you have to use the black and red wires for - they connect to a normally open set of contacts on the PTT switch.  Try the mic impedance switch in the high impedance position.  Note that as the PTT switch in the mic is wired, you won't be able to use VOX in the TR7 as the mic will be disconnected from the TR7 mic input unless the PTT switch is pressed.  What I'd do is to remove the green and yellow wires from the PTT switch in the mic and solder them together.  This will provide a path for the audio to the TR7 regardless of the PTT switch position and will not ground the audio line to the white wire as it does now.  You'll still need to use the red and black wires to control the TR7 PTT line. 

73, Floyd - K8AC
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KEVIN1218
Member

Posts: 19




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« Reply #2 on: February 25, 2013, 04:57:07 PM »

Thank you very much Floyd, I expect to wire it tomorrow night & hopefully success. I will also take your advice & solder the two wires together.

Very much appreciated.

73's
Kevin
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KEVIN1218
Member

Posts: 19




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« Reply #3 on: February 25, 2013, 06:50:34 PM »

K8AC Floyd......Rather than wait till tomorrow night I just returned home and could not resist wiring the mic now & give it a quick test.

The good news is that it is now keying the transmitter but the bad news is that it does not seem to have any audio input (certainly no output). When I depress the PTT it activates the Transceiver but the transceivers S/Power meter goes the opposite way.....negative

I suspect it's the mic wiring. Any suggestions?

Thank you,
Kevin
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K8AC
Member

Posts: 1478




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« Reply #4 on: February 26, 2013, 01:13:48 PM »

A couple of thoughts.... I don't know if the TR-7 is new to you or not, but if so, make sure that you have the mic gain turned up! Did you remove the green and yellow wires from the switch and solder them together?  If so, the switch is out of the audio circuit and the mic is connected to the TR-7 mic input regardless of position of the PTT switch.  So, putting the TR-7 into VOX mode and speaking into the mic should key the TR-7.  If none of that works and you're sure the wiring is correct, it's possible that the mic element is bad.  I don't know what the output voltage of it is, but you may be able to wiggle a multimeter on the millivolt scale just to see if you're getting anything out.
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KEVIN1218
Member

Posts: 19




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« Reply #5 on: February 26, 2013, 01:27:09 PM »

Thank you again Floyd....I did not remove the green & yellow wires from the switch and solder them together as you instructed me to do because I am not a fan of using VOX. Must this be done now to get audio? The microphone is new but that really does not guarantee anything, I will check that as well.

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KE3WD
Member

Posts: 5689




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« Reply #6 on: February 26, 2013, 01:51:41 PM »

If you are testing in SSB mode, don't forget that you must say something into the mic or whistle in order to see RF defection in that mode.  There is no carrier.


73
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