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RCA/Shure Model # MI-559156

 

Greetings,
I've a RCA/Shure Model # MI-559156 that I am trying to find a schematic or user manual for.
This mic looks like a 444 or 444D & has a Shure Brothers sticker on the bottom but has some unique circuit construction in the base.
The mic element has only 2 connections so it is not the 444D element.
There are 3 or 4 resistors & a capacitor inside the base and has black, white, red, green cable wire.
I did search old messages here & the interweb but haven't found anything.
I also contacted Shure to no avail.
This is my last hope!
?
73 Bob
 

Hi Bob

When I searched Google for:

"MI-559156" filetype:pdf

Two results came up:

Shure OEM Model Prefixes
PDF
MI-559156. 344A4611. 122037. 209468P3. GE. 559853D1. 99A86. 99B86. Base station, 6418, RCA, 97B140D (444var.?) Condenser, amplified, DTMF, handheld, Ericsson/GE ...

South Hills Amateur Radio Club
RCA ?(Courtesy of the RCA and the RCA 500 Series two-way radio forum.)
MI-559156-(4 COND. STK. #241762) TERM. A, B, C & D. MI-559156-A(6 COND. STK. #241763) TERM. A, B, C, D & F. MI-559156-A1(8 COND. STK. #244033) TERM. A, B, C ...

The RCA500mic.pdf contains some MI-559156 relateded amplifier circuits.?

For more information and if other micbuilders don't have any more details on the MI-559156, you can try contacting the South Hills Amateur Radio Club in Pennsylvania. If you're lucky, they may ask their members for a (copy of) a manual or schematic diagrams. at

Hope this helps!

Heinz?

Am Do., 13. Feb. 2025 um 03:37?Uhr schrieb Bob W8RMV via <W8RMV=[email protected]>:

Greetings,
I've a RCA/Shure Model # MI-559156 that I am trying to find a schematic or user manual for.
This mic looks like a 444 or 444D & has a Shure Brothers sticker on the bottom but has some unique circuit construction in the base.
The mic element has only 2 connections so it is not the 444D element.
There are 3 or 4 resistors & a capacitor inside the base and has black, white, red, green cable wire.
I did search old messages here & the interweb but haven't found anything.
I also contacted Shure to no avail.
This is my last hope!
?
73 Bob
 

Thanx Heinz.

Never thought of searching for a pdf. Duckduckgo didn’t find that.

I did more surgery on it & in the base there is a small amplifier in it.

It has a RCA branded 2N408 germanium PNP that tests good as does the mic cartridge.

It also has a 10uF 15 V cap that surprisingly tests very good for value & ESR.

I imagine 8-12 vdc would be a good supply voltage.

I may reachout to the SHARC’s & see if they have anymore.

Or I may just bypass it to use with my Tempo One transceiver.

?

Thanks again - Bob

?
 

Heinz,
I looked again at the RCA handmic link you sent & think I found the schematic for mine.
It shows an unidentified PNP along with the resistors & cap that is on my mic's board.
?
Thank you again!
-Bob
?
?
?
 

Bob,
?
I have bought some very old and dirty microphones at flea markets or recycling stores. I am not a professional micbuilder, but I am always happy when I can find technical information about the microphones and give them a new life.
?
Btw: I also searched on SHARC's website for 559156, but it seems the RCA handmic PDF is the only information they have.
?
559156 site:https://sharc.net/
?
Heinz
?
On Thu, Feb 13, 2025 at 11:54 AM, Bob W8RMV wrote:

Heinz,
I looked again at the RCA handmic link you sent & think I found the schematic for mine.
It shows an unidentified PNP along with the resistors & cap that is on my mic's board.
?
Thank you again!
-Bob

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