[Hallicrafters] vibrator how it works

[Glen Zook]

There are vibrators that vibrate at higher frequencies
as well as lower.  Those that were used by Motorola,
General Electric, and other commercial two-way
manufacturers (i.e. Motorola 48-847730 vibrator that
was used in many thousands of mobile units) reversed
the voltage approximately 120 times per second which
approximates 60 Hz AC.  

During the 1960s (and into the 1970s) before the
Japanese got into the amateur radio FM market it
definitely was very common to build base stations from
vibrator powered mobile units by using a heavy duty
filament transformer.  Many of these units operated 24
hours a day without any problems with the
transformers.

Now some vibrator units operated at much higher
frequencies which, of course, required much less
"iron" in the power transformers.  This was done to
reduce the weight of the equipment especially in
portable units, just like was done in airborne
equipment which used 400 Hz AC.

Those vibrators used in automobile receivers were
often of the type that reversed the voltage 240 times
per second which does approximate 120 Hz AC.  This
probably was to cut down on the expense of the power
transformers (again, less "iron").  Those used in
radios made for use in the old windcharger 32 volt
systems varied all over in terms of frequency.  I have
seen those that run under 100 times per second voltage
reversing and over 300 times per second.

My primary experience with vibrator type power
supplies is from the two-way radio market.  My junior
year in college I worked for the Motorola Service
Center in Atlanta, Georgia, and my senior year I
worked directly for Motorola.  I owned the Motorola
reconditioned equipment center for the south-central
U.S. from 1970 until Motorola went out of that end of
the business in 1979.  Of course by 1970 we were not
reconditioning any vibrator type units and, in fact,
only reconditioned completely tube type mobiles for
only 1 order and that was in early 1970 (20 "T" power
lowband units).

Glen, K9STH


--- Edward B Richards <zuu6k at juno.com> wrote:

Just to be a nit-picker, I believe most vibrators
vibrate at 120 cps not 60 cps. There are special
vibrators that do vibrate at 60 CPS but it takes a
heavy armature to vibrate that slow. Also, connecting
a 60 CPS source to the transformer can cause problems
as the transformer was designed for 120 CPS. Please
don't shoot me.









Glen, K9STH

Website:  http://k9sth.com

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