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          SECN is a 501 (C3), Tax ID # 45-5354176 for the Carolina 440 UHF Link System

Equipment Needed for System

We use a variety of legacy equipment for our system.  GE, Kenwood, Motorola, Tait, Vertex.

What we need mostly is the Motorola GM-300 or M120 UHF, 25 or 40 Watt radios with the 16 pin accesory that will program in the Amateur UHF Band for linking. See description below:

       with 16 pin option connector

GM300, MAXTRAC, M120.  You must make sure the radio has a 16 pin option connector.  The 5 pin radios DO NOT have COS at the plug .

GM300 shown here

Pin-Outs for ALL Motorola 16 pin radios

TX audio in=2 * a 10UF Non-polarized DC blocking cap in series may be required

PTT = 3
Gnd = 7
= 8 active low on carrier or valid PL
     NOTE: on 16 & 32 ch models, this pin is 
               programmable for other functions

RX audio out = 11


  1. As long as the microphone is inserted and hung up on the clip, the PL will be enabled. To operate the node without a microphone plugged in,  make an RJ45 mic plug shorting the PL line (PIN 3) to ground (PIN 4). To enable the front panel speaker, jumper 15 to 16

  2. On most of the Maxtrac radios, the feature which forces PL to be enabled when the microphone is hung up (clip button on back of microphone grounded) can be DISABLED when programming the radio.  This is under the radio-wide options screen along with the TX timeout value which can be set to OFF. Neither of these are default settings.   TNX Bob AC0KC

We also use GE Mastr II Euipment as well, so VHF and UHF parts for this equipment we use as well.  Especially UHF 50 Watt + Power Amplifiers, 50 Amp linear power supplies and Band Pass / Band Reject Duplexors and associated equipment.

We use commercial UHF Yagis, usually 5 and 6 elements.

Surplus Coaxial feed line, Heliax 1/2, 7/8 etc.

We use Micro Computer Concepts RC-100 and ARCOMM RC-210 repeater controllers.

Advance Receiver Research, P432VDG AR2 GaAsFET pre amps.

Tower Space

We are always looking for tower space, abandoned or not in use UHF antenna systems, equipment, etc. 

We could use locations to compliment the system presently in the Wake Forrest-Youngsville area to cover Falls Lake, Areas in Sanford, Pittsboro and Newton Grove are needed.  We also welcome anyone with UHF repeaters in NC, Virginia that would like to be a part of the Carolina 440 network, full time or on demand. 

Please give us a call or e mail and we would be glad to explain how this could be done if you are interested.

SECN has liability Insurance policy from Mercer Insurance Company to cover site work on our systems.

Anyone with:

Technical knowledge on two-way radio and IT experience to offer

Tower Riggers with Certifications and working relationship with a variety of Tower Companies.

Surplus UHF equipment

Grass cutting

Carpentry Skills

Contact via e-mail Ronnie J. Casey, This email address is being protected from spambots. You need JavaScript enabled to view it.

©2001-2018 Carolina 440 UHF Link System, A Non-Profit Division of Southeastern Emergency Communications Network, Corp. All rights reserved.
Ronnie J. Casey • K4JDR at • 84 Angie Road Raleigh, NC 27603-7336
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