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Identification of a
Motorola Quantar Station
By Martin A Flynn W2RWJ
Many of the photos in this article are clickable into larger images. All photos and images were taken by the author unless otherwise noted.
The station is a Motorola Quantar, 125-watt, continuous duty, 132-154 MHz with the optional high-stability oscillator.
Why I purchased a Quantar and not a Ham repeater:
A health-care system was evaluating use of ham radio for backup communications. I had a chance to provide them with a loaner during the evaluation. However, since the site also hosts multiple ambulance, fire, police, and other government systems, interference or interaction would not be tolerated at any level.
A previous user on the site was removed due to interference. Since the site has N+1 power, data, and decent height, I was designing a system that would prove well-behaved and (hopefully) be allowed to stay in place once the trial was over. It does not hurt that the Quantar station is a system of choice for public safety communications.
One thing that sets the Quantar apart from the MSF and MSR stations is that schematics are not readily available. Modules or FRU (Field Replaceable Units) are swapped in the field. This does make it a bit difficult to work on.
Near identical unit to my R1 Quantar station. My station also has the X873AA ultra high stability oscillator (UHSO). This model is officially known as a T5365A.
Where To Begin:
The quickest, most non-invasive method of identifying the basic band of a Quantar station is to look at the receiver module on the right side of the card cage. A 700/800/900 MHz station will have no holes. A UHF station will have 5 holes, but only three will have tuning slugs visible. A VHF station will have five holes, with 5 tuning slugs visible.
If the station is in the desired band, the next step is to look at the rear of the unit and read the part number label on the power amplifier module. It is usually visible without removing the module.
There are two different numbers you may encounter - the OEM (Original Equipment Manufacturer) modules used during assembly at the factory and if any modules have been replaced, FRU (Field Replaceable Units). If this is the case, you will see different part numbers, typically with "LN" in the second and third position.
The FRU and OEM units are the same components - one is a repair part, the other is a factory-installed module.
All VHF Range 2 (150-174 MHz) equipment will tune and operate down to approximately 146 MHz.
Power Amplifier Modules:
If the number on the PA (power amplifier) is highlighted in red, the next step is to remove the exciter to verify that it has the correct part number for the station. However, on the exciter and receiver modules, the manual references a third part number (CLx) in the "Factory Option Matrix". At least one of these, CLD1260 crosses to the TLN3251 in MOL. However most do not cross in MOL.
Any of the three part number formats could possibly be found on a Quantar exciter module. Most importantly, they all refer to the same component.
Each receiver module is made up of the receiver itself and the preselector. The same part number identification system as the exciter modules applies.
CAUTION: Make sure both the AC and DC (if so equipped) power is disconnected from the station before removing or inserting any modules. An ESD strap is recommended as well.
Each module is held in place in the card cage with two T15 Metric Torx screws. On the 100-watt stations, a short coaxial jumper feeds the power amplifier module from the exciter in the adjacent position in the card cage. This needs to be removed prior to removing the exciter or power amplifier. All modules unplug from the backplane as you slide them forward.
Quantar Bonus Items:
The Quantar station may be equipped with several items that make it more attractive for amateur use:
A Quantar station will program on amateur frequencies with the stock Radio Service Software (RSS). Please do not ask me for a copy. The local two-way radio shop programmed my Quantar for a fee.
Handy Part Numbers for Accessories:
Test Equipment Used:
Doug (AKA Batdude) for his excellent article on BATLABS, which provided a basis for my work.
Larry (AKA Astromodat) and XMO for their identification of the infamous Quantar exploding power supplies.
The staff of www.repeater-builder.com
The author can be contacted at: his-callsign [ at ] arrl [ dot ] net
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This page originally posted on Wednesday 19-Mar-2009
Article text, photos, artistic layout, and hand-coded HTML © Copyright 2009 by Martin A Flynn W2RWJ.
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.