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Post by vanlifeson on Oct 9, 2021 11:09:38 GMT -5
I see people selling 776’s with a 2 prong plug.
I have read that these were made for MK4’s
And that they got their power from the radio.
My question is, will a 776 wired for a MK3 be a power mic???
Thank you!
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Post by 2600 on Oct 9, 2021 21:51:39 GMT -5
This is a hack. A clever one, though.
Not only has the plug on the end of the cord been changed, the mike has been rewired inside to work with a Mark 3 transmitter.
This mike was included with the Mark 4 and 4A. With the original 4-pin plug it uses one pin to borrow 12 Volts DC from the transmitter to power the preamp circuit board inside.
The 110-Volt DC relay coil in the Mark 3 transmitter draws roughly 10 mA.
By an odd coincidence, the amplifier in the 776 draws nearly the same current.
The transmit switch in the mike originally connects the relay coil to ground when it's keyed. Instead, the switch now connects to the power wire of the mike's preamp, NOT ground. The relay in the transmitter now gets its ground connection through the mike's preamp circuit. The relay coil won't care that it now only gets about 100 Volts instead of 110 Volts DC. The mike preamp "borrows" some of the voltage drop that was powering the relay coil.
No idea who worked this out. I said "no way" first time someone told me that mike would work on a Mark 3.
Until I looked inside one that was set up this way.
BTW, if you want to use this mike on a Mark 4A, you will need both the original plug, and you'll have to restore the original wiring inside the mike.
73
P.S. If a Mark 3 transmitter has been modified to use relay with a 12-Volt coil in it, this trick will no longer work. We routinely do this to eliminate the mike's shock hazard when the factory relay has to be replaced. This hack works only with the original high-voltage relay.
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Post by vanlifeson on Oct 10, 2021 8:57:43 GMT -5
Wow. Interesting. Thank you!
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