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Old Turner Mic Wiring Question




 
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Author Topic: Old Turner Mic Wiring Question  (Read 2519 times)
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WO4K
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« on: December 21, 2015, 08:55:59 AM »

Recently I acquired a nice old Turner U9S mic (the variable impedance version of the Turner 99) that I want to try on my DX-100B. It has a two pin mic connector. One of my projects over the next few days is to build a short cable for it. The mic cable will have the female two pin connector on one end and an Amphenol 75-MC1F on the other. My question is this: for this mic, which of the two pins is hot (making the other common/ shield)? Corollary newbie question: on two pin mic connectors is there a Universal Law of Microphone Connections that states something like: "It is so written and shall always be thus: wherefore thou dost wireth a connector containing two pins, not more, not less, then now and forever hereafter #1 pin shall always be used for shield, and shield shall be #1 pin and no other"? In other words, on two pin connectors, is one pin universally used for shield?

73 and Merry Christmas,
Frank W4FLN
(Who needs to quit watching old Monty Python movies.)
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w4bfs
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« Reply #1 on: December 21, 2015, 10:15:13 AM »

(Who needs to quit watching old Monty Python movies.)

yes, just don't let them warp yer brain

the microphone issue is best resolved by dismantling at the output connector ... the multi-impedance implies an output transformer/autotransformer .... they generally used 40 ga wire so resistances will be fairly high ... you can use your oscope to find out which one gives the most output voltage to feed yer tube transmitter and to see how much asymetry you have in your voice when you talk
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It would from many blunders free us.         Robert Burns
M0VRF
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« Reply #2 on: December 21, 2015, 10:22:58 AM »

A wild guess here as I really haven't a clue as I don't know the mic but.....

Buzzz out the connector.

Does either pin go directly to any METAL part of the mic?

If so then I guess then you've answered the question but if no then.....

The mike may be 'Balanced' and have no earth but an overall screen to the cable which would be connected to the metal of the connector case.

Hmm...

JB.
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W9ZSL
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« Reply #3 on: December 21, 2015, 03:05:01 PM »

Try contacting Oak Tree Enterprises.  They actually have cables which are wired for the Turner with the correct connector on one end and an XLR on the other.  There is information available including a utube demo if you Google Turner U9S.  It appears that the connector at the mic is an Amphenol type. I'm guessing but when the switch is in the unbalanced position, two pins would be connected to the shield via the mic case and connector. It should be easy to check with an ohmmeter.  Switch the mic to high Z and see which pins get shorted to the connector shell and mic case.  How many pins are on the mic connector?  There should be 3 according to what I've seen on eBag. I'd bet pin 1 is shield, 2 is negative and 3 is positive.  If that were the case, switching to unbalanced would short pins 1 & 2 together leaving #3 as your hot (+) lead.  If 1 & 3 are shorted, then #2 is positive. Regardless, checking for continuity between the mic case and the pin / pins will tell you which pin is your shield.  Only 1 will show continuity in the balanced position.  That will be your shield regardless.

In any event, this simple test will allow you to determine the shield pin and the positive pin.  The pin left over will be your negative if used balanced.  In unbalanced mode, that pin should be shorted to your shield pin.

Unfortunately when you go back to 1940's vintage gear...or 50's for that matter, there was no official standard for mic wiring.  It differed between manufacturers.  Shure, for example, designated pin #3 as positive.  I have a 535 mic which is dual impedance and when switched to high, pins #1 and 2 are shorted together to the case and shield; pin #3 is positive. The connector is identical to the Turner's. There were even some companies that designated pin #3 as ground/shield!  Currently on XLR connectors, #1 is shield/ground, #2 is high side (+) and #3 is low side (-) if balanced. That is now standard, "It is so written."  Amen and Merry Christmas!
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