MCX100 radios - The Canadian Syntor

MCX100 radios were engineered and manufactured by Motorola Canada Ltd. in the 1980's using circuitry very similar to the Syntor. Performance is as good as current commercial radios and, with their small size plus scan and pl options, make great radios. (picture)
Characteristics
  • Control heads have LED channel indicator, volume and channel knob, non adjustable squelch on/off button, one or two digit channel LED, and additional buttons depending on options.
  • The frequency algorithm is virtually identical to the Syntor. Frequency is held in an inexpensive 82S129 bipolar prom.
  • The radios are about half the size of a Micor or Syntor trunk radio. Integral control head radio uses the same Microphone as a Syntor or Micor.
  • Speaker, although appearing the same as the Syntor is a 2 ohm speaker as no output transformer is used.
  • These radios trade hands for as little as $10 as access to programming hampers most users. They use an inexpensive bipolar prom for frequency, and similar proms for pl and scan options.
  • Squelch action better than a Micor - absolutley no tails.
  • Sensitivity 0.25 or better - no preamp available or needed.
Options
  • Two channel switches: 16 and 32 position binary encoded. The 32 channel switch is no longer available from Motorola.
  • Remote head: about 2 by 2 by 8 inches and 20+ foot cable. Microphone hard wired to backside.
  • Front ends: Standard helical was 4.5 MHz bandwidth, the wide one was 6 MHz and a dual wide was used to cover non contiguous frequencies. For example, one could have the weather channels (receive) and ham frequencies in the same radio without compromising out of band rejection.
  • Output: 10W or 30W - I have never seen the 10W version
  • VHF band splits: Range I 114.6-162 MHz Range II 124.6-174 MHz Bits in the prom set subrange. Use high side injection on Range II radios to receive below 146.
  • UHF band splits: Rand I 403-430 Range III 418.6-470 (there is no range II)
  • PL: optional board uses 82S129 bipolar prom. Enabled with front panel button and hangup box.
  • Scan: optional board uses 82S129 bipolar prom. Enabled with front panel switches. Many variations of scan available.
Useful Hints
  • Stops were used to mechanically limit to fewer channels. Remove knob and nut and discard the stops. A toggle switch can be added to the front panel to extend the 16 channel radios to two banks of 16.
  • Tune the helicals and local oscillator filter. Most radios are under deviated at 3.5 kHz from the factory. Crank up the VCO MOD.
  • Too many times when the radios are removed from service, the power cable is discarded and the frail cable connector lock is lost. Power connectors are $6+ from Motorola but if you paid $5 for your radio that doesn't seem like much of a bargain. Remove the main radio board and hardwire leads to the inside of the power connector using two fused leads, 1 or 2A for the controls and 10 A for the PA.

Consider building the bipolar prom programmer and contact me about software to produce the MCX-100 bit pattern to drive it.

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