A Crow bar is a place where birds get drunk!
Well in radio terms it is a circuit that protects the power supply from
putting out high voltage due to the regulator transistor shorting closed.
In order for your power supply to put out a regulated 13.5 volts the DC
voltage must be higher than 13.5 V. At the DC bridge there is 25 volts DC
this goes to an output transistor which in on the back of the power
supply in the heat sink. This transistor is controlled by the regulator
board after it senses the out put voltage this is how, under differing
current levels the voltage stays the same. The problem in older T*T
supplies is if the out put transistor fails. If it shorts open there's no
problem you just loose power, however if it fails by shorting closed you
have 25 volts going right to the rig. Crow bar is there for this problem
if the voltage goes high it causes a fuse to blow thus protecting your
dear rig.
Anyone else add something more? Scott don't ever feel bad about asking a
question it's the best way to learn. The dummies are the guy's like me
that tear into everything and ask questions too late.
73 Jeff aa8ve Save the planet Restore an old Ten*Tec!
On Fri, 19 Nov 1999 16:35:26 -0600 "Fike, Scott A. (OfficeVision)"
<SFIKE@twa.com> writes:
>
> Okay; I'm going to show my ignorance here, but that hasn't stopped
> me
> before.
> What is this "crow-bar" thing I keep reading about in Ten Tec power
> supplies?
>
> Thanks for any replies...
> 73
> Scott,KC0BUS
>
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