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"The Motorola MICOR Conversion Site"
Most of the information presented on this site was compiled by
Kevin Custer W3KKC and is Copyright © 1995 - present, all rights reserved

   

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Note that in Motorola's product line you have either a "mobile" or a "station",
and the latter is a fixed station - either a base or a repeater.

How to identify your MICOR    Mobiles are on the top, scroll down for stations
Here's a simpler MICOR Mobile identification table


Jump to:       Generic MICOR (both Mobile and Station)   Read this section first

Generic Station Information      Low-Band Station      High-Band Station      UHF Station

Generic Mobile Information      Low-Band Mobile      High-Band Mobile      UHF Mobile

Channel Element Info       222 MHz. Conversion       Packet       Other Information      Images

Custom Built Repeaters


Useful MICOR Manuals        Click here for how to order manuals
Motorola made a separate manual for each frequency range, and instead of duplicating all the pages on the control shelf in each one combined all the non-frequelcy sensitive sections into a separate manual.   To work on your base or repeater you will need BOTH the "Control and Applications Manual" AND the appropriate RF manual.

Base and Repeater Control and Applications Manual 68-81025E60 (non-RF information common to all stations)
Compa-Station Base & Repeater Radio 25-50 MHz 100 watts 68-81013E60 (Low Band)
Compa-Station Base Radio Remote Control 132-174 MHz 68-81013E65 (High Band)
Base and Repeater Station 450-470 or 470-512MHz 68-81025E50 (UHF)
Mobile UHF (standard and wide spaced) 68P81015E70
Mobile high band 68P81008E40
Mobile high band wide-spaced supplement: 68P81014E15

MICOR era radios have relatively narrow RF bandwidth. The maximum separation between two transmit frequencies in a standard high band MICOR is spec'd in the manual at 1.5 MHz, however, according to an original MICOR design engineer at Motorola, the exciter is capable of operating 3 MHz wide if it is center tuned 1 MHz above the lowest frequency.   The wide-spaced mobile series offered variations with wide-spaced receive, or transmit, or both.   The wide-spaced receiver has a second oscillator / multiplier and front end, the wide-spaced transmitter has a second exciter multiplier chain, thus one high band radio can have two 1.5 MHz (3 MHz) wide windows separated by up to 12 MHz from each other, and the channel switch selects the appropriate front end or exciter as well as which channel element.   The high band wide-spaced supplement is 68P81014E15 (note that the main high band mobile manual is 68P81008E40 - you will need both manuals for your wide-spaced radio).   The wide-spaced manual also has the information on the high-band extender-equipped receivers.   The regular UHF mobile manual has both the standard and the wide-spaced info.

The Spectra TAC Connection...
The name "Spectra" is used in two very different Moto product lines: there is the Spectra mobile radio, which has it's own page here at Repeater Builder.com, and there is the Spectra TAC receiver voting product ("TAC" = "Total Area Coverage" in the Moto catalog). What does this have to do with the MICOR? The Spectra-Tac receiver is a separate rack mount chassis with the model number TLN1991x (where "x" is an A or a B) regardless of the frequency band (low band, high band, UHF, 800mhz or 900mhz. This chassis holds a MICOR receiver board and any supporting circuitry. The TLN1991 is not a receiver. It is, according to Motorola, a "Receiver Housing Assembly" that is used for all models of SpectraTAC voting and satellite receivers. It is the rack-mounted box that contains the receiver, power supply, and any modules or cards) that are used in the particular application. These cards resemble those in a MICOR repeater control shelf however the cards are NOT compatible with a Micor shelf, and Micor cards are not compatible with a Spectra-TAC shelf. Most surplus Spectra-TAC chassis have a self-contained AC power supply, but some ran from external 12vDC. These chassis are useful as point-to-point link receivers, or when you need to convert an ex-wireline paging base station into a repeater. In most cases you will find a model number plate (or a model number stamped on the unit) in the format of:
C03RTB1108C for a High Band Voting Receiver without PL
C04RTB1018C for a UHF Band Voting Receiver without PL
C03RTB3108C for a High Band Voting Receiver with PL
C04RTB3108C for a UHF Band Voting Receiver with PL
N03RTB1100C for a High Band Satellite Receiver without PL
N04RTB1100C for a UHF Band Satellite Receiver without PL
N03RTB3100C for a High Band Satellite Receiver with PL
N04RTB3100C for a UHF Band Satellite Receiver with PL
The leading "C" indicates Compa series cabinet, a leading "N" indicates no cabinet was shipped with the unit. The "03" indicates 136-174MHz, the "04" indicated 406-512MHz. The RTB indicates a base station Micor line product, the next digit as a 1 indicated carrier squelch, or a 3 indicates PL. The Next 1 indicates narrow band. The 00 indicates one frequency satellite receiver, the 08 indicates 1 frequency and a voting encoder.


Spectra TAC Voting and Satellite Receiver Instruction Manual, 6881039E45, about $12 in Feb. 2007.
Spectra TAC Comparator Reference Manual, 6881039E50, also about $12 in Feb. 2007.
Both contain full specs, installation, maintenance, troubleshooting, schematics, board layouts, and parts lists for the receivers, all plug-in modules, the power supply, and the chassis / backplane. There are sections for VHF low-band (25-50), mid-band (72-76), and high band (132-174), UHF (406-512), and 800 MHz (806-821) receivers. The later revisions contain the information for the 900 MHz receiver.


Information Relevant to Both MICOR Mobile and Station:

The MICOR Squelch     Explanation of the MICOR® Bi-Level Squelch.     By Kevin Custer W3KKC
MICOR® based squelch circuit   A SEITS article
Explanation of Reverse Burst & "And" Squelch     By Kevin Custer W3KKC
Pre-emphasis, de-emphasis, clipping, and audio quality in the MICOR   By Paul Sexauer K3VIX
MICOR Muteboard®, muting audio filter amplifier     By Kevin Custer W3KKC
Modification of the MICOR PL Encoder   In some situations you want to disable the reverse-burst capability   By Kevin Custer W3KKC
COS Logic Level Inverter  A simple circuit to make positive logic COS from the audio-squelch board for those controllers that require it   By Kevin Custer W3KKC
MICOR® discriminator buffer amplifier     Great for NHRC, MCC, and other newer style controllers that mute and have de-emphasis built in
MICOR® PL® filter   By Kevin Custer W3KKC
An "S-Meter" for the MICOR Receiver   While this circuit was originally developed to allow a repeater receiver to drive an analog input of an ACC repeater controller there is no reason that it couldn't drive a different brand of repeater controller or even a meter...
Schematic of the TLN-4310B-2 mobile audio-squelch board   scanned from the mobile manual
This is oriented horizontally, for viewing on your screen.
Schematic of the TLN-4310B-2 mobile audio-squelch board   scanned from the mobile manual
This is oriented vertically, for printing (you will probably want to print it on legal paper, as it is an extended length diagram. If you are going to do any bench work, I'd suggest printing it on 11x17 paper.
Information on MICOR Channel Elements   By M. Scott Zimmerman


Non-Band-Specific Station Information:
Note that the controller connection articles are also applicable to other brands of controllers...
Comprehensive conversion of the MICOR® Compa-Station base/repeater station   By Kevin Custer W3KKC
Synthesize your MICOR Station   By Greg Carttar (ex-WAØLCZ) of 3rd St. R & D Production Services   (offsite link)
Modification of the MICOR PL Encoder   In some situations you want to disable the reverse-burst capability   By Kevin Custer W3KKC
Notes on how to simply connect a generic repeater controller to a MICOR station  By M. Scott Zimmerman N3XCC
An IDer for the MICOR Repeater Shelf    By Jerry Matthews WA0UZI
Useful to the commerical repeaters as the amateur radio repeater controllers have built-in ID'ers
One method of connection of a repeater controller (an S-COM) to the MICOR station  By Bob Hoffman N3CVL     (off-site link)
Another connection of a repeater controller (an S-COM) to the MICOR Unified Chassis Station   However this technique will work with any controller that can accept active low COR and PL decode signals and output an active low PTT signal (i.e. one that goes to ground).   By Joel Huntley WA1ZYX     (off-site link)
Modification of the older Station Control Module TLN4635B   (Click here for parts layout)    When using a repeater controller.   By Kevin Custer W3KKC
Modification of the newer Station Control Module TLN5970A (or later)   When using a repeater controller.     By Kevin Custer W3KKC
Modifying the TRN4662 Squelch Gate Module as an interface to an external controller   By Richard Reese WA8DBW     (off-site link)
Modifying the TRN4662 Squelch Gate Module for better operation as a repeater controller   By M. Scott Zimmerman N3XCC
Conversion of the MICOR® TRN6006 series Station Audio & Squelch board   For better audio muting   By Kevin Custer W3KKC
Using a converted TLN4310 MICOR® mobile audio & squelch board in a base/repeater station   By Kevin Custer W3KKC
Conversion of the MICOR Compa-Station Receiver Interconnect Board   By Kevin Custer W3KKC
Documentation on the TLN5167A Intercom, TLN5900 and TLN5993 Station Metering Kit, and TLN1859 and TLN1887 Metering and Intercom Kits   Donated by Eric Lemmon WB6FLY


Parts layout of the TLN4635: original (180kb)  enhanced (616kb)  enhanced & rotated (616kb)     Provided by Eric Lemmon WB6FLY
The "enhanced" file has a bit of contrast tweaking by WA6ILQ.   The rotated file is properly aligned for printing.
BTW, if you need replacement or additional card guides for the MICOR station card cage they are part number 45B83914G01 at about $2 each


Station Power Supplies:
Full manual for the TPN-1095A, TPN-1096A, and TPN-1102A station power supplies   5.8mb PDF file.
This was a high-resolution scan provided by Don Kovalchik, W8DPK; it was subsequently reduced in size.
Schematic of the TPN-1105 and TPN-1106 station power supply   128kb
The TPN-1105A can be wired for either 120 or 240vAC, but the TPN-1106A is 120v only.   The manual for either one is 68-81104E92.   This supply has the automatic power fail changeover feature.
Schematic of the TPN-1110 station ferro-resonant power supply   144kb  
This schematic is from manual 68P81020E44-N and covers both the TPN1110A and TPN1110B models that provide unregulated 13.8v at 25 amps for the PA deck plus 12v and 9.6 volts regulated.
Schematic of the TPN-1151 and TPN-1152 station power supplies  73kb
The TPN-1151A is 120/240v, but the TPN-1152A is 120v only. This is a fully linear supply with separate linear regulators for the +9.6v, low and high current 12v voltages.


Low Band MICOR Station:
Conversion of the MICOR Low-band receiver to the 6 meter amateur band     By Kevin Custer W3KKC
Conversion of the MICOR Low-band exciter to the 6 meter ham band   By Kevin Custer W3KKC
Another conversion site for MICOR Low-band to 6M Ham Band   Offsite link to KB6MIP's site


High Band MICOR Station:       (220MHz mods are in the 220 section below)
Comprehensive Description of the MICOR "Sensitron" Hi-band Receiver   By Kevin Custer W3KKC
Conversion of the MICOR "Sensitron" High-band Receiver to the 2m Ham Band   By Kevin Custer W3KKC
Now available: 132-150.8MHz helical resonator coils   Get a real 2 meter front-end for your MICOR receiver!   By Kevin Custer W3KKC
Modification of the MICOR Exciter   By Kevin Custer W3KKC
VHF MICOR PM to FM Exciter Modification   Convert your PM exciter to True FM!  By Kevin Custer W3KKC 
VHF MICOR tuning instructions   By Kevin Custer W3KKC
Retuning the VHF MICOR Bandpass Filter   By Kevin Custer W3KKC
A Conversion of a high band MICOR Intermittent Station to a Repeater   By Lawrence Glaister VE7IT
Documentation on the high band MICOR Preamp model TLD8421B and 8422B   Donated by Eric Lemmon WB6FLY
Note that if you need a preamp and can't find one that AngleLinear sells a very nice drop-in preamp, and a mounting bracket is available.
Conversion of the MICOR High-band Factory Preamp To The 2m Ham band   By Kevin Custer W3KKC
MICOR High Band Service Sheet Pg 1   This is Moto manual 68P81101E02-M Page 1.   Donated by Eric Lemmon WB6FLY
MICOR High Band Service Sheet Pg 2   This is page 2 of the above.
Micor DVP VHF Station Manual 6881036E40-B (no longer available): Complete manual (41.8 MB)
In sections: Pages 1-122 (16.8 MB)   Pages 123-165 (12.3 MB)   Pages 166-187 (12.8 MB)


UHF MICOR Station:
Repair notes and schematic for the UHF Station Tripler   By Bill Hance KD7CWA
Conversion of the UHF "Sensitron" Receiver to 440MHz Ham Band   By Kevin Custer W3KKC
Additional Info and Images about the above conversion for 435-450 MHz   By Robert Meister WA1MIK
Documentation on the UHF preamp model TLE8191A and TLE8192A  531 Kb PDF 6 page file from Eric Lemmon WB6FLY
Note that if you need a preamp and can't find one that AngleLinear sells a very nice drop-in preamp, and a mounting bracket is available.
Modification of the UHF Exciter   By Kevin Custer W3KKC
Tuning the UHF Station BPF's and Circulator (antenna network)  By Kevin Custer W3KKC


Information relevant to MICOR Mobiles being converted to Repeater or Link duty:
Notes:
1) The MICOR mobile chassis has a heat sink rated at only 35 watts - yes, that fact is in the MICOR mobile manual. Therefore radios higher than 45 watts are best left in mobile service.
2) The VHF Micor transmitter power amplifier stages use PNP transistors where the UHF radio uses NPN in the same area. Be careful when you do a rebuild that you have the right parts !!!
3) The normal mounting of a Micor mobile has the circuit boards upside down in the top of the case facing downward. As such the pinout is not what you would expect. Here is a drawing of the pinout viewed from outside the radio, looking at the front.

Generic Mobile Information:
Front casting modification for a second antenna connector   By Kevin Custer W3KKC
Duplex modification of MICOR mobile audio & squelch board   By Kevin Custer W3KKC
MICOR Muteboard®, muting audio filter amplifier   By Kevin Custer W3KKC
Modification of the MICOR PL Encoder   In some situations you want to disable the reverse-burst capability.   By Kevin Custer W3KKC
COS Logic Level Inverter   For making positive logic cos from the Audio-Squelch board.   By Kevin Custer W3KKC


Low-band MICOR Mobile:
Conversion of the MICOR Low-band receiver to the 6 meter ham band   By Kevin Custer W3KKC
Conversion of the MICOR Low-band exciter to the 6 meter ham band   By Kevin Custer W3KKC
Another conversion site for MICOR Low-band to 6M Ham Band     Offsite link to KB6MIP's site


High-band MICOR Mobile:       (220MHz mods are in the 220 section below)
Duplex conversion of a standard VHF mobile to repeater   By Kevin Custer W3KKC
Duplex conversion of Railroad VHF mobile to repeater   By Kevin Custer W3KKC
Duplex conversion of a VHF mobile to a repeater station By Jim Reese WD5IYT
Duplex Conversion of the mobile antenna switch   By Kevin Custer W3KKC
VHF Exciter Models   An explanation of the 3 different exciters common to the VHF radio.   By Kevin Custer W3KKC
VHF PM to FM Exciter Modification   Convert your PM exciter to True FM!   By Kevin Custer W3KKC 
VHF board model number frequency ranges An explanation of the board numbers on a VHF MICOR.   By Kevin Custer W3KKC
132-150.8MHz helical resonator coils for the MICOR  Get the right coils for your 2 meter front-end.   By Kevin Custer W3KKC
Comprehensive Description of the "Sensitron" Hi-band Receiver   By Kevin Custer W3KKC
Conversion of the "Sensitron" High-band Receiver to Ham Band  By Kevin Custer W3KKC
Modification of the VHF Exciter   By Kevin Custer W3KKC
Retuning the VHF Bandpass Filter   By Kevin Custer W3KKC
VHF tuning instructions   By Kevin Custer W3KKC
Documentation on the high band preamp model TLD8421B and TLD8422B   Donated by Eric Lemmon WB6FLY
Note that if you need a preamp and can't find one that AngleLinear sells a very nice drop-in preamp, and a mounting bracket is available.
Conversion of the High-band Preamp To Ham Band   By Kevin Custer W3KKC
Documentation on the 45 watt VHF PA deck   3mb PDF 15 page file from Eric Lemmon WB6FLY
High Band Service Sheet Pg 1   This is Moto manual 68P81101E02-M Page 1. Donated by Eric Lemmon WB6FLY
High Band Service Sheet Pg 2   This is page 2 of the above.


UHF MICOR Mobile:
A Technical Explanation of the MICOR UHF Mobile Radio Set   A walkthrough of how only one channel element / crystal can work for receive,  transmit repeat and transmit simplex.   By Kevin Custer W3KKC
Motorola's own technical description of the UHF MICOR Mobile Radio   Section 4, all 33 pages of it, from the official manual.   By Kevin Custer W3KKC
Duplex conversion of MICOR® UHF mobile to repeater station   By Jim Reese WD5IYT
Information on the UHF Mobile Low Level Amplifier (LLA)   How to increase the life expectancy     By Jeff DePolo WN3A
Conversion of the MICOR "Sensitron" UHF Receiver to the UHF ham band   By Kevin Custer W3KKC
Modification of the MICOR UHF Exciter   The standard Motorola microphone has a preamp inside the cartridge, and the radio supplies DC voltage on the mic audio lead to run it. This writeup shows how to get rid of it.   By Kevin Custer W3KKC
Documentation on the UHF preamp model TLE8191A and TLE8192A  531 Kb PDF 6 page file from Eric Lemmon WB6FLY
Note that if you need a preamp and can't find one that AngleLinear sells a very nice drop-in preamp, and a mounting bracket is available.
Emergency Medical Systems Duplex / Repeater UHF Mobile Radio manual supplement     PDF file courtesy of K9ROD
This is the no-longer-available manual supplement for the full-duplex dual-receiver repeating ambulance radio model Q2033 and Q1853.   Note that you need the regular UHF mobile manual 68-81015E70 to go along with it.
Note this is a 16.6 MB file - you better have broadband or plan on an all-night download...
Just right-click and "Save As".


Custom Modifications, Conversions and Parts Supplier for MICOR® Mobiles and Stations:
MICOR Repeater Conversions from Repeater-Builder
Custom Conversions by Kevin Custer and Scott Zimmerman from a certified Motorola Service Shop (MSS)


Channel Element Info
MICOR channel element schematic diagrams and other information   (with photos)   by Scott Zimmerman - N3XCC


220 MHz. Modifications for the MICOR High-Band Radio
Comprehensive Conversion of the MICOR High-Band Receiver to 222 MHz  By Kevin Custer W3KKC (new method)
Comprehensive Conversion of the MICOR High-Band Exciter to 222 MHz  By Kevin Custer and Scott Zimmerman (new method)
Conversion of the MICOR VHF exciter Band-Pass Filter to 220MHz   By Lee Woldanski VE7FET
MICOR 222 Mc. Modifications   Considerations from SEITS


Packet Modifications for the MICOR:
9600 baud modifications for the UHF MICOR   By Verne Buland


Other information relating to the Motorola MICOR:
Other Motorola information at WA8DBW's web site     By Richard Reese  WA8DBW offsite link


Scanned Images:         Most are oriented for printing, not viewing...
MICOR palm microphone schematic   21k
MICOR mobile radio interconnect board relay area   118k
MICOR Mobile Audio & Squelch Board layout   157k
MICOR Audio & Squelch Board schematic   166k
MICOR High-Band Exciter Board layout   157k
Picture of the MICOR mobile control head back side   38kb
MICOR mobile control head schematic   261k
The wide-spaced UHF mobile has both channel select and repeat-offset on/off lines.   A common modification on these radios in amateur use is to take the repeat offset on/off line and connect it to a spare lead in the cable rather than into the channel element selecting diode matrix.   A SPST switch is frequently installed in the control head just for repeat / simplex selection.   The Syntor series of radios (they can be though of as synthesized MICORs) had a optional faceplate for the clamshell head that was made just for this purpose (the switch is labeled "R" and "S").   This faceplate will fit the MICOR head perfectly.

A second common modification is to rectify the design oversight in the MICOR "clamshell" control head: there is no receiver PL control switch - a "Monitor" switch, if you will.   The designer expected you to use a microphone clip with a switch in it... with the microphone in the clip the PL was on, out of the clip you are in carrier squelch (monitor) mode.   One solution to this problem is to cut the trace on the control head PC board between J1101 pins 4 and 15 (not easy to do, but can be done with patient work with an X-Acto knife after using solder-wick to remove the excess solder) and jumper the cut with a SPST toggle switch.   This new switch when shorted will enable the PL decoder (by cutting the trace and bridging the cut with the switch it is placed in series with the microswitch in the hang-up box).


Engineering Notes provided by various reliable sources:

Subject - MICOR High-Band Exciter transmit frequency spacing.
Bob Swoger, K9WVY points out that the Motorola manual is in error when it states the High Band MICOR Mobile has a transmitter spread of only 1.5 MHz.  That is what the marketing group told the sales force.   Actually, the transmitter spread is 3 MHz on the standard production radio.  The designer of the first MICOR HB exciter was Jim Cox, a non-ham and laid off shortly after the MICOR shipped in 1970 due to the fact that he was the oldest and losing his hair.   That first exciter board was single sided and had grounding problems due to not enough copper foil.   This was a problem with the early PC board layout people.   They wanted to start with a non copper clad board and add copper.   Engineers wanted them to start with a double sided copper clad board and remove copper.   Jim's board indeed was only 1.5 MHz wide. Soon after another engineer named Don Nicklos (spelling?) made a double sided board that solved a lot of problems with proper grounding.   Don told me the new board could easily do 2 MHz and more.   I checked it out and found it could do 3 MHz.   Marketing was dead set against changing the published spec.

Then the State of Wisconsin put out a request for bid for high power high band radios with a transmitter spread of 2 MHz. GE could do this with their standard MASTRII. The MICOR as advertised would require the Wide Spaced Exciter option which would cost $150 more than the GE MASTR II as I recall.   My boss at that time had heard that I was running a MICOR mobile on 2 meters without a wide spaced exciter option and called me into the office.   He asked me to prove the standard product was as wide as I claimed it was by testing the radio between –40C to +70C.   I found I could get more that 3 MHz transmitter separation if I tuned the exciter 1 MHz above the lowest frequency.

We beat GE by $5 per box and won the contract. So, please change the web page to indicate the exciter is 3 MHz wide if it is center tuned 1 MHz above the lowest frequency. -- Bob

About Bob Swoger  My name is Robert E. Swoger, K9WVY.  I was at Motorola from 1965 until I retired in 2002.   I was in the original MICOR Mobile design team from 1969 on.   Not only did I design new MICOR radios, I later designed and FIXED designs of standard and custom MICOR Mobile and Bases.   When I wrapped it up I was in the design team of Saber, Cosmos and Spectra radios.

Several of the correction and additions to this site have been made by Bob Swoger, thanks Bob!
Kevin Custer and the Repeater Builder Group.


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Motorola® and MICOR® are registered trademarks of Motorola Inc.
Image(s) used with permission of Motorola Inc.

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.