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Radar Sentry

 
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jimthom1

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Since: Jan 01, 2005
Posts: 13



(Msg. 1) Posted: Sat Apr 26, 2008 4:35 pm
Post subject: Radar Sentry
Archived from groups: rec>boats>electronics (more info?)

I purchased one of these from Ebay:

http://www.guysoflidar.com/museum/the-first-commercial-radar-detector...

They show up occasionally on Ebay; first manufactured in 1961, when
the police in some states were use X-band radar to detect speeding
vehicles. They may not be sufficiently sensitive to pickup a ships
radar in time to be of any use, but at <$20 they are worth testing
versus the >$500 C.A.R.D.

Cheers, Jim

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Larry

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Since: Nov 05, 2005
Posts: 1286



(Msg. 2) Posted: Sun Apr 27, 2008 2:39 am
Post subject: Re: Radar Sentry [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)

jimthom.RemoveThis@optusnet.com.au wrote in news:897efd44-c79b-4335-95de-
57125fd78296.RemoveThis@u36g2000prf.googlegroups.com:

> I purchased one of these from Ebay:
>
> http://www.guysoflidar.com/museum/the-first-commercial-radar-
detector...
>
> They show up occasionally on Ebay; first manufactured in 1961, when
> the police in some states were use X-band radar to detect speeding
> vehicles. They may not be sufficiently sensitive to pickup a ships
> radar in time to be of any use, but at <$20 they are worth testing
> versus the >$500 C.A.R.D.
>
> Cheers, Jim
>

Be informed those old units radiated like hell and will JAM anyone's
radar that picks up the stray X-band radiation from them. When their
radar scanner points in your direction, they will see a sectorized blob
from its CW Xband output blanking out your radar return so they cannot
see where you are. This radiation is caused by the poorly designed
local oscillator in the old X-band radar detector's waveguide cavity, a
Gunn Diode on approximately 10.525 Ghz.....

The jamming will make you invisible or nearly invisible when you are
close to the radar equipped boat....when he needs to see you the most.

Radio Shack used to sell an X-band radar detector that is quite large,
has an octagonal black metal case with two knobs and a big red light on
it. It made such a great radar jammer for the cops, the FCC stepped in
from law enforcement complaints against it and forced RS to stop its
sale. I have one, just for grins...(c;

Cops use Ku (24.5 Ghz) band for more accuracy, smaller stealthy antennas
or laser scanners, now.

By the way, the magnetron out of a Raytheon Pathfinder (AN/SPS-21 in the
Navy) made an excellent radar jammer for the old "Speedmeter" analog cop
radars on X-band back in the 60's. Speedmeters had a silver transceiver
that hung out the left rear window of cop cars with the flat side
pointed forward. Coupled with a stock 27db feed horn, the 1KW peak
power magnetron would blow the mixer diode clean out of the Speedmeter
as you passed by him pulsing 1KW into the 27 db feedhorn. His meter
pegged negative with no mixer....a failure mode...(c; I never did this,
of course, just heard of it....(c;

Why someone hasn't started marketing Taser-proof conductive clothing to
short out the HV from a taser fired at you remains a mystery to me.

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jimthom1

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Since: Jan 01, 2005
Posts: 13



(Msg. 3) Posted: Mon Apr 28, 2008 3:20 pm
Post subject: Re: Radar Sentry [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)

Larry, does this mean my poorly designed oscillator will behave like
an active radar reflector?
Cheers, Jim

> Be informed those old units radiated like hell and will JAM anyone's
> radar that picks up the stray X-band radiation from them.  When their
> radar scanner points in your direction, they will see a sectorized blob
> from its CW Xband output blanking out your radar return so they cannot
> see where you are.  This radiation is caused by the poorly designed
> local oscillator in the old X-band radar detector's waveguide cavity, a
> Gunn Diode on approximately 10.525 Ghz.....
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Larry

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Since: Nov 05, 2005
Posts: 1286



(Msg. 4) Posted: Fri May 02, 2008 5:55 pm
Post subject: Re: Radar Sentry [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)

jimthom DeleteThis @optusnet.com.au wrote in news:ec052890-aba9-4c1e-9c5c-
b11d660ff2db DeleteThis @y22g2000prd.googlegroups.com:

> Larry, does this mean my poorly designed oscillator will behave like
> an active radar reflector?
>

No! Your poorly designed oscillator will behave just the opposite.....

A reflector makes you BIGGER as a target on someone's radar.

Your oscillator will make you INVISIBLE in the CW noise it creates when
their antenna is pointed in your direction....
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Richard Casady

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Since: Jul 11, 2007
Posts: 111



(Msg. 5) Posted: Sat May 03, 2008 7:02 pm
Post subject: Re: Radar Sentry [Login to view extended thread Info.]
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On Fri, 02 May 2008 17:55:49 +0000, Larry <noone RemoveThis @home.com> wrote:

>jimthom@optusnet.com.au wrote in news:ec052890-aba9-4c1e-9c5c-
>b11d660ff2db@y22g2000prd.googlegroups.com:
>
>> Larry, does this mean my poorly designed oscillator will behave like
>> an active radar reflector?
>>
>
>No! Your poorly designed oscillator will behave just the opposite.....
>
>A reflector makes you BIGGER as a target on someone's radar.
>
>Your oscillator will make you INVISIBLE in the CW noise it creates when
>their antenna is pointed in your direction....

The Japanese painted a bridge with radar absorbing paint, probably
Ironball. This was so that ships radar would be able to see past the
bridge.

Casady
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Bruce in alaska

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Since: Jan 04, 2008
Posts: 27



(Msg. 6) Posted: Sun May 04, 2008 5:08 pm
Post subject: Re: Radar Sentry [Login to view extended thread Info.]
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In article <481cb5bc.1029657312 DeleteThis @news.east.earthlink.net>,
richardcasady DeleteThis @earthlink.net (Richard Casady) wrote:

>
> The Japanese painted a bridge with radar absorbing paint, probably
> Ironball. This was so that ships radar would be able to see past the
> bridge.
>
> Casady

That makes no sense at all.... If the bridge was reflecting the signal,
how would adsorbing that same signal cause it to travel beyond the
bridge? If the Bridge was left unpainted RF should go beyond the bridge
and any targets past it would come back later, in the Time Domain, and
be displayed as farther away.

--
Bruce in alaska
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