🚀 go-pugleaf

They must be putting some high voltage directly to the antenna wire.
The current source must be very low as in any of these portable HV
units.

You can try to put an NE2 neon lamp from the antenna input to the
electrical ground.  Do this directly at the receiver antenna input.
This is a little lamp that is a neon type lamp.  It illuminates at about
63 volts if voltage is applied to it.  If you apply voltage to it, a
ballast resistor is necessary.  The value depends on the applied
voltage.

In your case you want to use it as a hard voltage clamp.  Put a resistor
of about 27 to 33 ohms in series with the lamp, to allow isolation from
its capacitive characteristics.  The stray capacitance of the lamp is
about 3 to 5 pF.   If this will not effect the performance of the
antenna (it should not), then it should work for you.  In effect you
have the lamp that is in series with the resistor in parallel to the
antenna input to ground.   This is an old technique used by many
armature radio operators and short-wave listeners to protect their
receiver front ends from static electricity damage.


-- 

Greetings,

Jerry Greenberg        GLG Technologies GLG
==============================================
WebPage         http://www.zoom-one.com
Electronics        http://www.zoom-one.com/electron.htm
Instruments       http://www.zoom-one.com/glgtech.htm
==============================================
"DaveC" <dave-usenet3016@mailblocks.com> wrote in message
news:0001HW.BB56508400106C52F0386600@news.individual.net...
I am trying to fix a car alarm/remote locking unit. It seems that punks
are
putting personal protection "zappers" to the bumpers of cars and frying
the
receiver input.

The input is very simple: length of wire serves as antenna, connected to
input of wide bandwidth transistor driving tuned circuit.

Transistor is fried. How can I protect this from several thousand volts
(I'm
guessing here; what's the typical input from one of these zappers?)? Are
air-gap devices recommended?

Example p/n's would be appreciated.

Thanks,
-- 
Dave C
dave-usenet3016@mailblocks.com