Non Linear Junction Detector Metal Detector

[Old Fisher]

Hi All,
I'm a "newbie" to this site (great site!) & I'd like to start off here by asking a question. As a sideline I deal in Military Surplus and I just acquired two metal detecting units that are marked "non Linear Junction Detector" "Locater Pro Plus" these were formerly the property of the US Embassy in West Germany and I imagine they were used in Embassy security. Does anyone know what specifically these units would have been used for? Also, who manufactured them? I need a manual. Thanking all of you folks in advance.

Old Fisher

 

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[DakLak]

Non-Linear Junction Detectors

NLJD detect, using Radio Frequencies, 'interruptions' such as those that occur when two dissimilar conductive materials meet as in semiconductors or between different metals.

The NLJD was first used by the Russians to sniff out CIA audio bugs, and very successful they were, too, until the CIA, and company, starting inserting RF filters in the circuitry which prevented the Radio Frequency field from even penetrating the bugs.

They are still used to sniff out 'commercial bugs' (see Winkelmann < HAWK XTS-2500 Non-Linear Junction Detector >) and Improvised Explosive Devices used by Crusaders/Criminals/Crazies these days.

These days everyone knows how to defeat them, but the cheaper bugs don't bother with such features.

Hope this helps.