[Hallicrafters] vibrator how it works

[Glen Zook]

Basically a vibrator reverses the direction of a DC
voltage thus simulating an AC voltage as applied to a
power transformer.  Often this is done using a
transformer with a center tapped primary with the tap
going to ground.  The vibrator applies the DC voltage
(doesn't matter if the source is positive ground or
negative ground) to first one side of the primary
winding and then to the other side.  Most vibrators
reverse the voltage around 120 times per second which
approximates 60 Hz AC.

The voltage from the secondary of the transformer is
basically AC and has to be rectified to produce DC for
the unit to operate.

The recification can be accomplished either
electronically (i.e. with some sort of vacuum tube or
solid-state) or mechanically by separate contacts
within the vibrator that are 180 degrees out of phase
with the input voltage.  Vibrators which mechanically
"rectify" the high voltage are called "syncronous"
vibrators.

Back when most VHF FM units available to amateur radio
operators were obsolete commercial FM mobiles it was
very common to unplug the vibrator and to insert
either 6.3 VAC or 12.6 VAC from a filament transformer
(depending on whether the unit was designed for 6 volt
or 12 volt DC operation) to use the unit as a base
station.

Glen, K9STH


--- "Duane Fischer, W8DBF" <dfischer at usol.com> wrote:

For those among the hundreds upon hundreds of us who
populate this fascinating list, perhaps one of you
tech dudes would explain to those who do not know what
a radio vibrator does and exactly how it does it?
Thank  you.









Glen, K9STH

Website:  http://k9sth.com

__________________________________________________
Do You Yahoo!?
Tired of spam?  Yahoo! Mail has the best spam protection around 
http://mail.yahoo.com