Glen,
 
    Short answer: 
 
he MRC-67 series (specifically the MRC-67A) is a rugged, waterproof, and amplified loudspeaker designed by McDowell Research for military/tactical environments, such as vehicles or command centers. It monitors a single transceiver/encryption unit with 5W maximum output, 10–36 VDC power, and automatic muting when PTT is keyed. 
 
Specs here:  https://ultralifecorporation.com/wp-content/uploads/2025/12/TDS_MRC-67_Series.pdf
 
More info here with WIRING:  https://www.prc68.com/I/MRC67.shtml
 
I have used them and they sound OK.  They are well a well build quality item, very rugged.  We ordered them for many of our systems.
   
CAVEAT:  However, If I were in a non-tactical environment, and I was going to be using the system for a long duration, would replace it with something that is full range (i.e. sounds better)  
 
73,
Gene K1NR
GO PATS !
 
 
On 02/06/2026 7:42 AM EST Glenn Little WB4UIV via Milsurplus <[email protected]> wrote:
 
 
Does anyone have any information on this amplified speaker?
Would like a service manual, wishful thinking.
Or possibly the connector pin outs.

Thanks
73
Glenn
WB4UIV
-- 
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Glenn Little                ARRL Technical Specialist   QCWA  LM 28417
Amateur Callsign:  WB4UIV            [email protected]    AMSAT LM 2178
QTH:  Goose Creek, SC USA (EM92xx)  USSVI, FRA, NRA-LM    ARRL TAPR
"It is not the class of license that the Amateur holds but the class
of the Amateur that holds the license"
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