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  An Introduction to the
MSF5000 and PURC5000 Stations

Compiled and written by Mike Morris WA6ILQ
Maintained by Robert W. Meister WA1MIK
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According to the Motorola sales brochures from the era, the "MSF" stands for "Maximum System Flexibility". The MSF10000 is the European version, and the PURC5000 is a paging base station that is derived from the MSF5000 (the older plain "PURC" station was MICOR-based). The "PURC" was a marketing-generated abbreviation and stood for Paging Universal Remote Control, which was a paging-oriented modification to the standard tone remote control format for transmitter keying in both the analog and binary mode. Some MICOR-based PURCs and MSF-based PURC5000s had cross-band receivers (usually 75 or 900 MHz), others were analog wire-line controlled, others had modems that passed digital data from a leased digital wire-line to the transmitter. An interesting thread providing some PURC5000 station info can be found here.

The MSF5000 stations come in two basic types: those with "CLB" and those with "CXB", "RLB", or "GFB" in their model number. A "JLB" is a transmit-only (i.e. paging) version of a "CLB" (which used the marketing name of "PURC5000"), a "JXB" is the similar version of a "CXB", and a "JFB" is the similar version of the "GFB".

The "CLB" series (the first generation) are commonly called the "analog" stations and hold their parameters (RF frequency, PL tone or DPL code, etc.) in a 2732 family EPROM and are programmed via the R-1800/1801 suitcase programmer. If you have a "CLB" and don't have a suitcase you will need to find someone who does. You will only need it once to burn the frequency and configuration profile PROM for your station (unless you need to change frequency). And just having the suitcase isn't everything; the suitcase has to have the MSF firmware and EPROM-burning adapter installed in it. See this web page on what it takes to program a "CLB" series MSF (it's an offsite link).

Those units with "CXB" or "RLB" in their model number are the second generation MSFs and are commonly called the "digital", "digital-capable" or "digital modulation capable" stations and this simply means that the station can be equipped for encrypted communications - a 12 kbps [two level] digital SecureNet modulation format (DES / DVP). Note that the MSF were designed many years before P25 was even though of, and the digital modulation format is definitely NOT P25. The MSF secure option board enables the station to perform as a true digital repeater by regeneration of the recovered inbound data. It can also encrypt and decrypt analog audio from and to the station's analog wire-line (the leased circuit from the station to the dispatch console), enable repeat based on proper code detect, etc.

Units with "GFB" in their model number are commonly called "analog-plus"; they're "digital" too, but are not capable of secure communications (and could be exported).

The front panel control shelf on the MSF identifies the type of controller it has. First find the volume and squelch controls; they will be on a small sub-panel of the control unit. If you see a three-digit red LED display window at the right side of that sub-panel, then it's a "CXB", "RLB", or "GFB" that is programmed by a PC via a serial cable. If the red LED display is on the top left then it is a PURC5000. If there is no display at all then it's one of the "CLB" series that needs the suitcase programmer. A front panel photo of all three is at the top of this page, more photos of the CLB and CXB series are on the "Photo Tour" article in the MSF section.

All of the second generation units - the "CXB", "RLB" and "GFB" stations are programmed via a serial port, which can be accessed via the control or expansion jacks of the control tray. You will need a PC booted to DOS running Radio Service Software (RSS) product number RVN-4077G (the current version is R05.21.00) and a RIB and cable to connect to the MSF. The RSS must run under DOS, it will not run properly in a DOS BOX or under any version of Windows. There is an "RSS and RIB" web page on this web site that covers some of the details on them, and some of the limitations of the RSS software.

An interesting and informative thread on 800 MHz vs 900 MHz MSF stations and how to tell them apart by the model number can be read here. The short version: any Cn5xxx-n1nn (where x is a letter and n is a number) is 800 MHz and Cn5xxx-n2nn is 900 MHz.

All MSF5000 stations have an independent receiver and transmitter and can receive and transmit at the same time, in other words they can operate full-duplex. If an internal or external duplexer is employed, then the station can act as a repeater and utilize just one antenna. Alternatively, two separate antennas can be used to make a repeater. In either case, a received signal will cause the transmitter to be energized. The station can also be programmed as a base station, which implies some sort of wire line remote control, because the received signal will NOT key the transmitter. An antenna relay is used to switch the single antenna to either the receiver or the transmitter, or two separate antennas could also be used. The main point is that the station can be configured - with the appropriate hardware - to run as either a base station or repeater station, and it's usually easy to convert between the two. PURC5000 stations are merely the transmit half of the full MSF5000 station; all of the internal receiver circuitry is missing.

EBay buyers: beware! No matter WHAT the model tag says, no PURC, MSF or PURC5000 station will ever operate over the entire 132-174 MHz or 403-475 MHz frequency band listed on its model tag / label! Each station will do only a portion of that model tag frequency spread, called a "split", a "band-split" or a "range". This is a simple law of physics.

Unfortunately, there are only two ways to determine the band-split of your station. You either have to read the code plug (with RSS or the suitcase programmer) and look at the information it displays, or you have to find a tag or number stamped on a major frequency-sensitive assembly (PA, RF Tray, VCO) and check the last digit. If it's a "1", the station is "Range 1"; if it's a "2", the station is "Range 2". The various ranges are detailed in the "MSF5000 Photo Tour" article in the MSF section - look for the heading "Selected Station Ratings and Specifications". You may notice some yellow/orange labels on the lower left corner of the RF tray casting and on the VCOs in some of the photos; as this is a Range 2 station, the last digit is "2" for all of these assembly numbers.

The CLB (analog) stations have an identifier whose spacing is locked at 15 minutes, and whose tone frequency is locked at a specific tone frequency. These two characteristics contribute to the fact that almost every analog station I've seen in amateur service has been programmed as a duplex base station (with no IDer) and fitted with an external controller (that does the ID and a lot more).
I've heard rumors that someone has identified the various locations in the firmware that control the IDer and has changed:
a) the spacing to 9 minutes and 55 seconds (to make it ham-radio-legal)
b) the tone frequency to 1064 Hz
c) the chip checksum to make the byte differences in the above two modifications "legitimate" so that the rest of the programming accepts it.
If anyone has the above info please share it with repeater-builder so we can share it with others.

There is a known bug in the MSF programming software that programs the digital stations. Unfortunately it's never going to be fixed as the MSF line has been off the support list for years.
The Auto ID Interval field will accept any value, but seems to reduce some to the next lowest 5, 10, 20, or 40 minute interval. You can enter 009 but it seems to change that to 000. All other values between 001 and 010 work fine. 11-14 get reduced to 10. 15 works fine, but exceeds the FCC rules for amateur repeaters. This isn't a problem with amateur systems that are configured with external controllers and disable the MSF internal CW ID.

Speaking of CW ID, the deviation level of the internally-generated tones (CW ID and alarm) is a fixed percentage of the total deviation and not adjustable. Many people complain that it is too loud. There are several ways to deal with this issue:

Once you start tuning up the MSF you will discover an annoying "gotcha": the MSF station does not have a speaker on the receiver, in fact it has a low level (1/2 watt) amplifier that was designed to drive the earpiece in the test handset and not much more. Due to this situation both models of the MSF5000 test set contain an amplified speaker. The TMN6164A test handset is extremely rare - I have seen exactly two in over 5 years on eBay. If you want to build your own it would not be hard to take any Western Electric or ITT "G" series telephone handset, put a PTT button on it somewhere, add a 620 ohm resistor in series with the earpiece, and if you can't find a 6-wire curly cord to crimp a 6-wire RJ-11 plug to just add a 6-wire RJ11-style cord to it (and yes, I know that a "real" RJ-11 has only 1 pair (two pins), a RJ14 has 2 pairs (4 pins) and a RJ-25 has all three pairs (6 pins), but nobody uses the RJ14 or RJ25 terminology. Everything in a 6-pin body is referred to as an RJ-11).

The HMN1001B microphone plugs right into the 6-wire RJ jack in the station control tray and allows you to locally key the transmitter and talk over it. There is just one problem: the HMN1001B is rather rare, and when found is usually expensive. A cheap equivalent is to take a common 8-pin (i.e. RJ45 style plug) microphone from a Maxtrac, Radius or GM300, an RJ45 jack with screw terminals (as opposed to punchdown style terminals) and a short 6-pin RJ11 silver-satin cord and mate them. Just take the pinout of the RJ45 microphone (available on the Maxtrac/Radius/GM300 page at this web site), the schematic of the TMN6164A test handset data sheet (which includes the pin-out of the connector) and make yourself a microphone adapter cable (and yes, I know that an 8-wire analog RJ connector is an RJ-61 jack, but everybody refers to it as an RJ-45). This gives you an inexpensive test microphone.
If anyone has the part number for the replacement cord for the HMN1001B microphone please let me know so I can add it here. One could be ordered and installed in any common Motrac/Motran/Mocom/MICOR etc. microphone and that would give one a cheap test mic.

Personally, I prefer having a common mobile microphone and a local speaker that has enough volume to be useful. As long as you are making up a microphone adapter, why not do the following: take a common mobile speaker, build up a common LM386 ampifier circuit on a piece of perfboard (see this page). Then mount the perfboard inside a mobile speaker case, with the volume control pot mounted in the outer case (or even in the center of the grille). The use of a pot with a switch allows turning the amplifier off when you aren't there. Then cable the amplified speaker into the RJ45 microphone adapter box: connect the audio input to pins 2 and 5 of the headset jack, mount the mobile speaker somewhere in the repeater cabinet, and pick up +12vDC for the amplifier from any of several places in the drawer. This gives you a proper local service speaker and a test microphone. Just remember to program the local mike as having the highest priority.

MSF5000s were sometimes equipped with a second receiver and control tray. Here's a photo of the control panel of the receiver's control tray. Here's a photo of the control board that's inside that control tray. Here's a photo of the top cover of the RF Tray. Here's a photo of the inside of the RF Tray. Note that the front panel resembles what you'd find on an older analog (CLB) station. Also the RF Tray is missing the IPA (Intermediate Power Amplifier) and the transmit VCO, because these aren't needed in a receiver chassis.

Expansion trays usually were equipped with a Wildcard module. This board has four digital inputs, four digital outputs, and up to four relays, that can be wired up to do all sorts of unique things, providing special features that customers ordered. Every unit was different and exact schematics are almost never available. The wildcard module usually looked at, and modified, data on the MUXBus, which is displayed with the Digital Metering Panel (that's the one with 64 LEDs on it). Here's a photo of the wildcard control panel in an expansion tray. Here's a photo of a wildcard circuit board in an expansion tray. Here's another wildcard and power supply circuit board pair in an expansion tray. The module at the right is a power supply regulator for all the other modules in the tray. This last photo by WA1MIK.

Another popular option was the DTMF Encoder/Decoder, which was programmed via RSS. These modules tended to be found in analog (CLB) stations, as the functionality was moved to the SAM for the digital-capable stations. This module also has limited speech output capability. Here's a photo of the DTMF control panel in an expansion tray. Here's a photo of the DTMF circuit board in an expansion tray. Both photos by WA1MIK.

Another option that was a bit more rare was the Station Access Module (SAM). This board was meant to replace the wildcard module, letting you do everything via software (programming through RSS). There are more inputs and outputs, a built-in DTMF encoder and decoder, and several software digital data decoders (such as MDC1200). In addition, it could perform limited diagnostics on the station and report many more error conditions. Here's a photo of the SAM control panel in an expansion tray. Here's a photo of the SAM circuit boards in an expansion tray. The right-hand board is for diversity reception operation. Both of these are documented in the "MSF5000/10000 Data Station Smart Wildcard and Diagnostic Options" manual.

Common terms and answers to Frequently Asked Questions:

Contact Information:

The author can be contacted at: his-callsign // at // repeater-builder // dot // com.

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Hand-coded HTML © Copyright 2006 and date of last update by Mike Morris WA6ILQ and repeater-builder.com.
This page created 26-Mar-2006 and split off from the main page 26-Mar-2010.
Analog and digital MSF montage photos taken by, and copyright © 2010 by Robert W. Meister, who also wrote and provided some of the text.
PURC5000 montage photo taken by, and copyright © 2010 by Knox LaRue and John Hymes.

This web page, this web site, the information presented in and on its pages and in these modifications and conversions is © Copyrighted 1995 and (date of last update) by Kevin Custer W3KKC and multiple originating authors. All Rights Reserved, including that of paper and web publication elsewhere.