Discussion in 'Ham Radio Discussions' started by K8MOT, Aug 2, 2017.

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  1. WA9WVX

    WA9WVX Ham Member QRZ Page

    Hi Sue,

    The MICOM engineering team only built one VFO version for Dayton Hamvention but were basically laughed out of that hamfest. All the rest of MICOM Product require an individual to enter the desired frequency of operation or press the up / down tactile buttons. The one thing that I liked was the SSB Squelch circuitry, that was slick. No other manufacture has attempted to bring out a similar circuit.

  2. WA9WVX

    WA9WVX Ham Member QRZ Page

    Hello Dan,

    If you can locate an electrolytic capacitor in your MICOM 104, they normally have a date code etched on to the side of the component. You might find four numbers like 8937 which would mean the transceiver was built in 1989, the 37 th week.

  3. AF6LJ

    AF6LJ Ham Member QRZ Page

    The squelch circuit really works.
    My 500E is sitting on the shelf waiting for me to get a hand mice interfaced to it.
    My 500E is also headless, which means I remote control it.
    Control heads cost more than the radio on E-Bay. :eek:
  4. K3XR

    K3XR Ham Member QRZ Page

    Appreciate the reply Dan I acquired the rig around 2005 used in excellent condition looked like it had little use get great reports when I fire it up on 60 meters switched to another rig because it only had 4 of the 5 channels for that band and one was changed to another frequency a few years back now I see International Crystal Manufacturing (ICM) is going or is out of business so quality crystals are getting harder to come by. This may prompt me to get it off the shelf.
  5. WA9WVX

    WA9WVX Ham Member QRZ Page


    You'll need a 600 OHM microphone fore that transceiver. I don't remember the type of the connector they used on those transceivers.

  6. AF6LJ

    AF6LJ Ham Member QRZ Page

    I have a pre amp design I am going to use.
    I have a homebrew control cable that has an audio circuit in it, PTT switch and 600 ohm isolation transformer.
    I just need to do this.....
    The project has been on the back burner for a while now and I promised myself I would get it done before the end of the year.
  7. WA9WVX

    WA9WVX Ham Member QRZ Page


    I believe that your MICOM 104 may be a 2 to 12 MHz crystal controlled transceiver. It's been at least 25 years since I worked for the MICOM International Engineering Department in Schaumburg doing HF studies on the frequency bands. Of course Motorola did away with their Crystal Department and International Crystal Manufacturing closed their doors on the last day in May, 2017 so you're now straddling a fence trying determine which way to proceed. Well I searched the internet and found that Bomar Crystals, JAN Crystals, Peterson Radio, Sentry Mfg Co, Crystek Crystals Corporation appear to still be in business. Take a look at this document: and here's a UK Crystal Manufacture QuartsLab : So it may not be as bad as you once thought it would be. On the other hand perhaps you could build a homebrew synthesizer for the TX & RX frequencies, you would have the problem fixed.

    AF6LJ likes this.
  8. K3XR

    K3XR Ham Member QRZ Page

    Good information Dan was surprised to see some of those crystal manufacturers are still in business have thought about the synthesier route also. Curious did Motorola in fact have a department that manufactured their own crystals or were they purchased from a company like ICM ?
  9. K9STH

    K9STH Platinum Subscriber Platinum Subscriber QRZ Page

    Motorola made the SSB equipment from the late 1960s through, at least, the late 1980s. Most of the equipment was housed in the new "Consolette" cabinets. The earlier versions used "channel elements" (separate crystal controlled oscillators) for frequency control.

    They also sold Vibroplex "Original" keys, with a Motorola C&E part number, that could also be used with the SSB base stations. In addition, various wire antennas and automatic antenna tuning units were available. The antennas had very long insulators and phosphor-bronze wire included.

    I still have at least one of the antenna tuning units, bits and pieces of a couple of the antenna kits, as well as the "instruction" pamphlet on the Vibroplex keys, at various places around my house. I will look for the pamphlet, get it scanned, and then upload the scan to this thread.

    Motorola sold TXU (the electric company by which I was employed for over 10-years) a complete SSB system that was installed at the various electric generation plants throughout the State of Texas. This system was tested and then completely forgotten. It was supposed to be in place for a "black start" (every generation plant completely "off-line") situation. By the time I was employed, every unit had been placed in some storage unit and most of the personnel did not have a "clue" as to even what the system was to be used let alone know how to operate the equipment. Most of the antennas were still in place usually being installed between 2 of the ventilation columns somewhere near the plant's main office.

    Glen, K9STH
  10. KK4YWN

    KK4YWN Ham Member QRZ Page

    I don't understand why squelch is even included on hf rigs. Its utterly useless.

    If an adjustable decay was added to the squelch it would work fine. Instead of slamming shut it should taper off.. that would work great on ssb.

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