Custom Products for the Repeater Builder

MICOR Analog Noise Squelch Board
For Two-Way Radio Applications

Model MS-25

Click Here for schematic, installation, and set-up instructions.

Ordering instructions on bottom of page.

The MS-25 is a professional, yet affordable, add on analog noise squelch detection system on a small printed circuit board.

This board can be added to any radio or repeater that has a suitable discriminator connection.

This board is completely through-hole construction to allow repair or modification by the common technician.

  It is used to create a quality noise squelch logic to be interfaced with a standard repeater controller or radio interface with AllStar.  
It doesn't mute or control the audio in any way.

This board uses the Motorola MICOR squelch chip for noise squelch detection.

Kit - you supply your own MICOR squelch chip - $25.00 each.
Kit with MICOR squelch chip - $50.00 each.
Assembled and tested without the MICOR squelch chip - $50.00 each.
Assembled and tested with MICOR squelch chip - $75.00 each.
Available in three different versions with the following squelch pot options: 3/4 turn, 25 turn vertical, or 25 turn horizontal.
All three versions are the same price each.
US shipping and handling $7.50 in small quantity.
PayPal accepted - order below.

NOTICE: My stock of new MICOR squelch chips has been depleted, HOWEVER, used - tested - and guaranteed chips are available.
I have a huge stock of these parts to fulfill orders way into the future.

Photo of three actual size MS-25 modules.   Three PC board versions are available.
(Click image to enlarge)

The MS-25 is a MICOR noise squelch on a small printed circuit board.   The board uses a genuine MICOR M6709 (SC6709 - M7716), as I have yet to find anything superior.   A socket is provided for the MICOR squelch chip.   If you cannot source this component yourself, it's available from me - see options below.

There are two differently colored LEDs for status.   One is blue, it indicates a valid carrier squelch detection.   The second is green which also indicates a valid carrier squelch detection, but it also verifies the transistor logic circuitry is operating properly.

About the inputs and outputs.
There are only three necessary connections for input; discriminator audio, power, and ground.

The logic outputs for COS are not totem pole, however, both active high and active low outputs are available.

Why do we need this board?
Not all radios have easy access to quality COS signal.   Some repeater hardware may not include a conventional squelch control or may require reprogramming just to change the squelch setting or PL tone.   Some radios simply have inferior noise squelches.   DSP in AllStar applications is good, but nothing beats a MICOR noise squelch.

There are three identical versions of the board, with one exception - the squelch control.   Some folks prefer a simple 3/4 turn control which mimics most standard squelch pots.   Some installations may require a precision vertically or horizontally accessed control.   You choose the version that will best suit your needs.   The 3/4 turn version is the most popular.

Power Source: +12 to +16 VDC recommended, must be constant, not switched.   Maximum voltage is 24 VDC.
Onboard regulation + 9.6V for the MICOR chip and logic.
Squelch control can be either simple 3/4 turn potentiometer, 25 turn vertical, or 25 turn horizontal control.
Low current draw, about 19 mA standby, (45 mA both LEDs lit), depending on logic sourced and its input impedance.
All logic is sourced from 9.6 VDC.   Pull-up and pull-down resistors are included.
Used/tested/guaranteed MICOR 6709 squelch chips avaiable until stock is depleted.
Small size - can fit inside many radios.
Add a quality squelch to that radio whose logic signals are hard to get to.
Great for AllStar - app_rpt or connecting up your favorite repeater controller!
Simple to hook up and set up.
90 day Limited Warranty.  Repair available for units out of, or not covered under warranty (my determination).
Mounts with double-sided foam tape or stand-offs (not included).
Hookup is made with a 6 position .100 female header connector and pins (both included).
Kit comes with pc board, thru-hole components, and a IC socket.


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MS-25 ordering options
Control Type
You may place an order but we'll not ship until after the 18th. Thanks for your understanding!!

Email Kevin Custer for ordering information, order by check, and/or quantity pricing of this exciting product.

Product of Kevin Custer - W3KKC, all rights reserved.
Specifications may change without notice.
Images are property of Kevin Custer - W3KKC
Board layout by Chuck Kelsey - WB2EDV
HTML November 15, 2014, W3KKC All Rights Reserved!