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NCS-AN-100A
Set-up Procedures for Using Various Type Microphones with the NCS-C250
1.0 Introduction
Most any microphone can be used with the NCS-C250 due to the ability to set impedance, level,
electret voltage and/or other auxiliary voltages required for certain microphones. Microphones
with dynamic or electret elements are most commonly used in communications applications and
are the focus of this application note. Additionally, requirements for microphones equipped with
preamplifiers and DTMF encoders are discussed.
Before attempting to set-up the NCS-C250 for use with a particular microphone you must have
certain key information about the microphone.
a. Is the microphone terminated in an RJ45 8 pin modular connector? This type
connector is required to interface with the NCS-C250.
b. Wiring diagram of the RJ45 connector
c. What type microphone element is used? Dynamic or Electret?
d. Does the microphone require an auxiliary voltage for proper operation?
This information should be detailed in your radio manual or in information supplied with the
microphone.
2.0 RJ45 Pin Numbering
Unfortunately, there is no standard in the communications industry for the numbering of the RJ45
pins. There are two possibilities for numbering of the RJ45 pins and radio and microphone
manufacturers use both. These are shown below.
1
8
Plug Cover
RJ-45 8 Pin
Modular Plug
Plastic Clip
on Farside
1
8
Plug Cover
RJ-45 8 Pin
Modular Plug
Plastic Clip
on Farside
