Collcomm NCS-AN-100A Installation and operating instructions

collcomm inc
April 5, 2014
A
AP PP PL LI IC CA AT TI IO ON N N NO OT TE E
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
18
Plug Cover
RJ-45 8 Pin
Modular Plug Plastic Clip
on Farside

collcomm inc
April 5, 2014
2
A
AP PP PL LI IC CA AT TI IO ON N N NO OT TE E
NCS-AN-100A
2.1 NCS-C250 RJ45 Pin Numbering
The pin numbering of the mic plug and the mic jack used on the NCS-C250 is shown
below.
A frequent point of confusion occurs when the microphone to be used with the NCS-C250
is numbered using the opposite convention. The first step is to determine whether your
microphone connector is numbered the same as the mic jack of the NCS-C250.
2.2 Determining Pin-outs for Your Microphone
Determining the pin-out for your microphone requires having the necessary pin-out
information from the microphone manufacturer. This information should provide a list of
the pin assignments and the numbering convention used for the RJ45 connector. Two
examples are shown below, the first is of a microphone with an RJ45 connector
numbered the same as the NCS-C250 and the second is of a microphone with an RJ45
connector numbered using the opposite convention.
1 8
Plug Cover
RJ-45 8 Pin
Modular Plug Plastic Clip
on Farside
18
Plug Cover
RJ-45 8 Pin
Modular Plug Plastic Clip
on Farside
E
En nd d V Vi ie ew w o of f R RJ J4 45 5 P Pl lu ug g
Looking into the RJ45 Jack
Pin Numbering Same as
NCS-C250
Pin Numbering Opposite
to that of NCS-C250

collcomm inc
April 5, 2014
3
A
AP PP PL LI IC CA AT TI IO ON N N NO OT TE E
NCS-AN-100A
Example of Microphone Connector Numbered Same as the NCS-C250 RJ45 Jack
Example of Microphone Connector Numbered Opposite from that of the NCS-C250
RJ45 Jack
The table of pin assignments is identical to the table in the first example; however, notice
that the RJ45 connector numbering is reversed. In order to convert the RJ45 numbering
to that used on the NCS-C250 use the following example.
From the above table, use the “NCS-C250 Pin Numbering” column to determine the proper
microphone jumper settings for the NCS-C250
Pin #
Function
1
NC
2
NC
3
NC
4
Ground
5
Mic Audio
6
PTT
7
NC
8
NC
1 NC
2 NC
3 NC
4 Ground 5 Mic Audio
6 PTT
7 NC
8 NC
Plug Cover
RJ-45 8 Pin
Modular Plug Plastic Clip on
Farside
Pin #
Function
1
NC
2
NC
3
NC
4
Ground
5
Mic Audio
6
PTT
7
NC
8
NC
1 NC
2 NC
3 NC
4 Ground
5 Mic Audio
6 PTT
7 NC
8 NC
Plug Cover
RJ-45 8 Pin
Modular Plug Plastic Clip
on Farside
Your Microphone Pin
Numbering
NCS-C250 Pin
Numbering
Microphone Pin
Function
1
8
NC
2
7
NC
3
6
NC
4
5
Ground
5
4
Mic Audio
6
3
PTT
7
2
NC
8
1
NC

collcomm inc
April 5, 2014
4
A
AP PP PL LI IC CA AT TI IO ON N N NO OT TE E
NCS-AN-100A
3.0 Setting the Microphone Jumpers in the NCS-C250.
The two diagrams below show the proper jumper settings for the two examples given previously.
Refer to the NCS-C250 Instruction Manual for additional information on installing these jumpers.
3.1 Electret Microphones
Electret microphones require a “phantom” voltage be applied to the mic audio line. If
your microphone is an electret type you must install the electret jumper. See the figure
below for placement of the electret jumper. The microphone will not work without this
jumper installed. DO NOT install this jumper if your microphone is a dynamic type.
Jumper Settings for Electret Type Microphone
Mic Audio
PTT
Ground
Unsel
Audio
AUXV
Sel
Audio 1 2 3 4 5 6 7 8
5V 12V
AUXV
Electret Voltage
Jumper
Mic Audio
PTT
Ground
Unsel
Audio
AUXV
Sel
Audio 1 2 3 4 5 6 7 8
5V 12V
AUXV
Electret Voltage
Jumper
Jumper Settings for Mic
Connector Numbered Same
as NCS-C250 Mic Jack
Jumper Settings for Mic
Connector Numbered
Opposite from NCS-C250
Mic Jack.
Mic Audio
PTT
Ground
Unsel
Audio
AUXV
Sel
Audio 1 2 3 4 5 6 7 8
5V 12V
AUXV
Electret Voltage
Jumper

collcomm inc
April 5, 2014
5
A
AP PP PL LI IC CA AT TI IO ON N N NO OT TE E
NCS-AN-100A
3.2 DTMF and Preamplified Microphones
If your microphone requires a separate voltage supply to operate a preamp, DTMF
keyboard or similar circuitry, a jumper must be installed on the AUXV block at the
corresponding microphone pin number. Additionally, you must select the desired voltage,
5V or 12V using a jumper on the AUXV jumper block.
The figure below illustrates the jumper settings for a DTMF microphone that requires a 12
VDC auxiliary voltage to be applied to pin 3 of the RJ45 mic connector.
4.0 Contact Us
If you have questions regarding setting up your microphone for use with the NCS-C250, contact
Collcomm at:
Tel/Fax: [phone]
Email: [e-mail]
Mic Audio
PTT
Ground
Unsel
Audio
AUXV
Sel
Audio 1 2 3 4 5 6 7 8
5V 12V
AUXV
Electret Voltage
Jumper