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From: gd@milkfs.itstd.sri.com (Greg DesBrisay)
Newsgroups: sci.electronics
Subject: Re: Radar gun zapper: fact or fiction?
Message-ID: <29392@sparkyfs.istc.sri.com>
Date: 5 Jan 90 19:02:34 GMT
References: <74719@psuecl.bitnet> <1198@ariel.unm.edu> <10657@ucsd.Edu> <3488@cbnewsl.ATT.COM>
Sender: news@sparkyfs.istc.sri.com
Reply-To: gd@itstd.sri.com.UUCP (Greg DesBrisay)
Organization: SRI International, Menlo Park CA
Lines: 28

>In article <10657@ucsd.Edu>, brian@ucsd.Edu (Brian Kantor) writes:
> A reasonably large magnetron feeding a reasonably large antenna on the
> front of your car, wired up to a bank of capacitors charged by an
> inverter from the car battery, might be able to emit a pulse of 10 GHz
> or 24 GHz of sufficient magnitude to blow the mixer diode in the typical
> cop radar to glory-be.  You'd clearly want to have it trigger off the
> radar detector mounted next to it, but shielded from it in some way.


Reliable rumor has it that some folks did just what you are
suggesting, but instead of the magnetron they used a spark plug!  The
spark plug was mounted in a tuned cavity which was in turn coupled to
a horn antenna.

Back in the early days of police radar, they filled the back end of an
automobile with capacitors (and in those days there was a lot of room
in the back of an automobile), charged up all those capacitors, and
then, as they drove by an unsuspecting "target", they discharged the
capacitors all at once through the spark gap.

They left more than a few radar operators scratching their heads,
wondering why their radar unit suddenly failed, but decided to curtail
their activity before someone associated the failure of the radar
units with the loud shotgun-like bang that happened whenever they
threw the switch on their spark gap!


Greg