MX340 Information wanted

[njh621]

A long time ago in a galaxy far, far away (ok not really)....the US Air Force operated Titan II ICBM sites, which had among its several communication systems a Radio-Type Maintenance Net (RTMN for short), which was built entirely by Motorola. The radio net consisted of a base station, a controller (with an override function), antennas that weaved throughout the complex, and MX340 portables. Recently I came across a maintenance tech order (the Air Force in their infinite wisdom documented EVERYTHING at these sties) for the system, which included among other things a part list with part numbers, Motorola part numbers.

I'll be posting the scanned pages with diagrams sometime soon. What can anyone tell me about the H23AAU1110B? The manual lists additional model information, SPO1T139.625MHZ (I'm guessing this is bandsplit info). Manuals (PDF or physical copies) and the like would be useful.

[Andy Brinkley]

The model # decodes to a crystal controlled MX-340, VHF 1 watt RF output, non secure carrier squelch radio. The SPO1 indicates a special Production radio, which could be anything.

[njh621]

Thanks for the info! I wouldn't be surprised if they were special production. Now the hard part is trying to found equipment like this (and at a decent price).

These are the diagrams I pulled from the maintenance tech order.

[Tom in D.C.]

The VHF MX340 used separate receive and transmit crystals. (The UHF units
used a single receive crystal plus a transmit offset crystal of 3 or 5 mHz.) The SP marking
can usually be figured out by having a person who knows MXs physically examine the radio, unless you can find something in the documentation you have discovered. I have a ton of
MX tech data on hand if you want to send me some photos of the radio, the most important
ones being with the back and front off.

Regards,

[njh621]

I don't have access to the radio on-hand (it's 2000 miles back at the Titan Missile Museum in Tucson), but if you glimpse at the tech data, there appears to be SP data. The types of transceivers used on site have the same data, SPO1T139.625MHz. Hopefully that helps, otherwise I'll have to email my contact at the museum and have him take pictures.

[dfc2]

You are right about the SP... it could be almost anything. I personally have seen single tone boards for access to repeaters, some high tech scann functions, even duel receieve with SP products.. I have seen a few I could not make heads or tails out of. the SPxx was listed on the radio but nothing look different.. could have been something deep inside the workings.. no clue.

The MX300-S/R were the best radios ever made...except you had to have the R1801 to programm it. they took a beating.....

DFC2

[abbylind]

Looks like they were on 139-141 Mhz

Fowler

[njh621]

That sounds about right. I don't know the exact freqs they used for TX and RX, but I know it was a VHF system.