Plantronics Supra SHS1585-01NC 992C Headset
New military communications headset w/6-pin audio connector. Plantronics
Supra Kit model SHS1585-01NC 992C has boom mic and hand PTT switch. Comes
in box with instructions. from American-Milspec.
Photos from American-Milspec. Scan
This headset has a simulates carbon mike and needs DC bias for operation.
It will need a wiring modification to work with the 5-pin mil radios.
The factory wiring is as follows:
Connector pin A, Black wire in headset cable = Microphone Common
Connector pin B, Red wire in headset cable = Microphone
Connector pin C, Yellow wire in headset cable = Speaker
Connector pin D, Green wire in headset cable = Speaker
Connector Pin E, Blue Wire in headset cable = PTT Switch
Connector Pin F, White wire in headset cable = PTT Switch
Conversion for Mil Radios
It turns out that this headset was made to replace a carbon mike unit,
but is uses some other kind of mike and active circuits for both the mike
The power for the circuits comes from the DC bias that the equipment
supplied for the carbon mike. The polarity does not matter since
there is a diode bridge in series with the DC power line. It wants
to see about 10 mA. This can be provided from a standard 9 Volt battery
and a 680 Ohm resistor. The top from a dead 9 Volt battery can be
removed and used as a snap connector. These are connected in series
between the outside black and red wires which are bridged across the black
and red mike wires going to the headset. A rubber band to hold a
pair of pliers closed makes a "third hand".
Rewire the connector as follows:
As an aside the customer service from Plantronics has been first rate.
This is a very high quality company. They also warned me that this
model is obsolete.
radio Ground - A = Black (mike com), Green (speaker), White (PTT) + black
wire to outside
radio Ear - B = Yellow (speaker) + 1 K Ohm
resistor to pin A (this is to mute the radio's internal speaker)
The PRC-68 wants to see a much lower resistor to mute the speaker,
some testing would be needed, maybe 27 to 47 Ohms.
radio PTT C = Blue PTT
radio mike D = Red (mike) + red wire
The above conversion does not work as well as it should. Someone
said that the grounds may need to be done differently?
Back to Brooke's Photo of Military Audio Accessories,
U-229 Audio Accessories,
Audio, PRC68.COM, Squad
Radio, Military Information,
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