More Information on Xilex IMTS Car Telephones

As per the main page, Xilex was located in Redding, California at 2540 Hartnell Avenue and was in business from approximately 1980-1985.  They made numerous models of multi-function mobile telephone controllers which were sold with modified RF packages such as  by Uniden, Pace and Standard, on VHF, UHF and 800 MHz.  The phones were capable of being configured to operate on practically any signaling format.

Xilex was unique in that it was a company which would build a phone to whatever specifications a customer wanted, and did many small orders.  This makes it harder to keep track of the models and variations.

In addition to the 4500 Series control head shown on the main page, which was also known as the MTM-8 (Mobile Telephone Model 8,) Xilex made the Model MTM-400, as shown below.  This was a Uniden dash mount mobile radio modified with the Xilex MTM-4A control board and pre-dates the 4500, which replaced it.  The original Uniden radio used a diode matrix for channel programming, but Xilex replaced the matrix board with a board of their own design using a pair of shift registers which were driven by an 8085 microprocessor.  The standard front panel was removed and replaced with a custom Xilex panel overlay with their own switches and lights, and where the speaker grille had once been, a keypad panel was mounted.  The handset was mounted below on a bracket, with a glass reed switch inside it and a magnet on the bracket (to detect hang-up.)

The MTM-400 could be delivered with IMTS or RCC firmware but also had DTMF, 2805, SMART, IPTS, AMTS, 5-Tone and 2-Tone signaling capabilities.  However, interestingly, it did not contain a duplexer.  The firmware allowed for IMTS use without a duplexer by sending a "keep alive" programmable pulse of carrier to keep the land terminal from thinking the mobile had gone out of range, but the unit was still push-to-talk in IMTS.  This is essentially the same way the Yaesu "Traveler" IMTS portable phone operates without a duplexer.  

Xilex's final Xilex-branded product was the MTM-800, which was sold for approximately the final two years of the company.  This used a three layer board stack but I am not sure of the actual physical appearance and do not have any photos.  If you have one of these or any data on it, please let me know!

Thanks to Phil Torre and Steven Inness of Xilex for sharing this information and the three photos below:

 

Xilex X-Tel 500

This is the same mobile telephone as was sold under the Transcon brand name as shown elsewhere on these pages.  The only difference appears to be the labeling.  See the Transcon 105 and similar models information for further data.

 

 

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Ver. 5-13-2013                                                                                                                                                  ęGeoffrey C. Fors  2010