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  Motorola Spectra TAC™ Receiver and Comparator Index Page
Compiled by Robert Meister WA1MIK
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Left: Spectra TAC Receiver. Right: Spectra TAC Comparator

This is the main index page for the Motorola Spectra TAC voting receivers, satellite receivers, and voter/comparator units. The various articles and information resources that have been collected or submitted to Repeater-Builder are listed below.

Both the voter chassis and the receiver chassis are three rack units high (5.25 inches).

Despite people calling everything in this chassis style a Spectra TAC receiver, they aren't.

Note from WA6ILQ:
The original design of the MICOR station had separate chassis for the receiver, exciter and control shelf, all linked by 50-pin ribbon cables. At that time multconductor ribbon cable and the insulation displacement connectors were a fairly new product and Moto had nothing but trouble with them. It wasn't long until Moto came up with a Unified Chassis design that eliminated the riibbon cables entirely (and after the the 50-pin ribbon cables and the insulation displacement connector products matured they lived on as the PC and mainframe SCSI-II disk drive intercabling).
Moto needed a second receiver for the unified MICOR chassis and the engineers took the early MICOR receiver chassis and did some redesign. They came up with a package that could function as a second receiver or even more (I've seen six in a system rack, each on a different channel), as a stand-alone auxiliary receiver.
The first Moto-designed voter system used DC current in a phone line to indicate signal strength. This system used cards in slot two and slot three. The later voter design (called "Spectra TAC") fit on one card and it went into slot three and slot two was used for the PL or DPL card. The fourth slot has always been for the metering/speaker card.


Spectra TAC Total Area Coverage Voting and Satellite Receivers Instruction Manual, p/n 6881039E45. Contains info on all MICOR receiver boards (low, mid, high, UHF, 800 MHz) plus the plug-in cards, power supply, and chassis. It has been reported that some copies also have documentation on the 900 MHz receiver boards. $13.50US in April 2010.
Spectra TAC Total Area Coverage Comparator Instruction Manual p/n 6881039E50-A. Contains info on the plug-in cards, power supply, and chassis. Scanned by Eric Lemmon WB6FLY. 5.7 MB PDF.
Spectra TAC Comparator Roofing Filter plug-in module documentation and a photo of the board courtesy of Greg Carttar.


Spectra TAC Receiver, Satellite Receiver and Auxiliary Receiver Information Page
The Aux Receiver / Satelite Receiver / Spectra TAC Receiver is a separate rack-mount chassis that holds a standard MICOR receiver board (low band, mid band, high band, UHF, 800 MHz or 900 MHz), plus supporting PC boards in card slots. This article also contains an extensive list of receiver boards. If you are trying to find out what frequency range a board is from the part number, look here. Compiled by Mike Morris WA6ILQ.
Spectra TAC Voter Notes
A collection of hints and tips for modifying the Spectra TAC Voting panel. Compiled by Kevin Custer W3KKC.
Spectra TAC Receiver Notes
Hints and tips for connecting and using the Spectra TAC receivers. By M. Scott Zimmerman N3XCC.
Using RF Links in Spectra TAC voting systems
Hints and tips for using RF links with connecting and using the Spectra TAC receivers and comparators. Also includes a brief history of Motorola's voter systems. Compiled by Robert W. Meister WA1MIK from notes by Greg Carttar.
Spectra TAC Gang Voting Interface Modification
This article shows how to use non-Spectra TAC receivers with Spectra TAC voters to save space and improve reliability. Couresy of Greg Carttar of 3rd St. R & D Production Services. This article was previously off-site; now it's here on Repeater-Builder.
Spectra TAC Receiver Timing Notes
The idle tone timing and protocol is critical to the proper operation of the comparator. This article shows the various delays and why they're needed. Written by Robert Meister WA1MIK.
Adding a DPL Decoder to a Spectra TAC PL board
An inexpensive DPL encode/decode board can easily be added to, and installed in, the Spectra TAC PL decoder board. This article describes the whole process. Written by Robert Meister WA1MIK.
Improving the Spectra TAC Receiver Service Module
Motorola should have put in a volume control with a knob, rather than the slotted shaft potthey ended up using. Here's a $5 solution that can be added in a few minutes. Written by Robert Meister WA1MIK.
Spectra TAC Receiver Audio Filters and Frequency Response
There's a high-pass (PL) filter in the Audio Control Module that does a very good job of removing PL/DPL signals, when it's enabled. The frequency response of this filter, as well as the low and high frequency equalization jumper settings, are all graphed. Written by Robert Meister WA1MIK.
A Spectra TAC System with RF Links and an MSF5000
A full-blown system with four Spectra TAC receivers and one Spectra TAC Comparator, using an MSF5000 as an additional receiver and the transmitter. Written by Anthony Stump KE4KQI.
Replacing SpectraTAC Micor Receivers with MaxTrac Radios
Now that crystals are nearly impossible to get, why not use a synthesized MaxTrac mobile radio to replace a Micor crystal-controlled receiver. Written by Anthony Stump KE4KQI.

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This page created 14-Apr-10 by Robert W Meister WA1MIK.

Motorola® and Spectra TAC® (and a bunch more stuff) are registered trademarks 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.