Then I started my career in Public Safety. Starting out I was
a Dispatcher. So, I used a radio a lot. But, it was push the button on the
console or activate the foot switch, no real interaction with turning knobs and
dials. However, all the radios have vacuum tubes in them. One of the base
radios that worked in the 40MHz range was a five foot tall cabinet. That
cabinet generated a lot of heat.
Then I went into the field division and had a little more
interaction with the radio. We had a squelch control (now squelch control is
mostly programmed into the radio), turn the switch to change frequencies and
the switch to choose which repeater that you wanted. The mobile radios at this
time were a “hybrid” in that the receiver was all solid state, but the
transmitter still had one tube (though not a glass envelope tube) in the final
Power Amplifier. The unit fit in the trunk and was large and heavy. Of course,
some of the cars still had radios in the trunk that required a dynamo to run.
When you keyed the microphone (held PTT switch) the dynamo started, and it
sounded like a jet taking off. After the dynamo hit peak, you could transmit.
Then we got fully solid-state radios. Not much smaller in
the trunk, the control heads were larger but that was because the siren\Public
Address board was part of the control head. We still had a squelch control and
the knob to change frequencies and push buttons to choose the repeater that you
wanted. These radios still had crystals in them that were “cut” to the proper
frequency. The crystals were housed in metal heater containers to make sure
that they would work at the proper frequency.
As time went on, I got acquainted with a gentleman that ran
the radio repair shop for a large construction company doing work in the area.
He had been in law enforcement, and volunteered with the local EMS and
volunteer Fire Departments. He was not into Amateur (ham) radio, just
commercial and Public Safety. From him I learned a lot about radios. With his
guidance I took several radios that had been donated by a federal agency to the
local search and rescue organization and replaced the crystals with new ones
and retuned them to work in the public safety band area. I learned how
repeaters worked, that a frequency split was necessary, that most were
activated with a CTCSS tone. That changing or adding a new repeater or changing
the CTCSS tone on a repeater meant a lot of work, as all the radios that
accessed that repeater had to be modified. I even started my own sideline
business of installing radios in Public Safety vehicles. It was not unusual to
see an ambulance, police car or fire truck in our carport while I spent days or
weeks installing radios. A lot of the installations had to have control heads
or at least microphones in the front and back of the vehicle. I learned a lot.
Then a promotion came, and I was assigned to administration.
Part of that job was management of the radio system and the fleet. It was about
time to change the radio equipment. It was getting a little ancient and though
it still worked well it was time to upgrade. So, with all the background and knowledge
gathered through all the years of radio interaction, we redesigned the system.
We relocated repeater sites, added a few and made the conversion to synthesized
radios. No more crystals. We used a computer to change the frequencies. We also
added Digital Voice Protection, or scrambling to the system. This was a
headache as the code had to be created and then loaded into each radio. But, it
worked well.
A change of jobs led me to yet another radio adventure. This
time it was to assist in the planning and implementation of a county wide
narrow band VHF simulcast system. This system would carry traffic for numerous
law enforcement, fire and ems agencies. What a project.
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