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Fisher 441
Posted by: Doctorcoinz
Date: August 20, 2017 05:05PM
Circa 1980 (or thereabouts) , what frequency does this all metal detector work on. Any experts who know?..thanks...

Re: Fisher 441
Posted by: Dave J.
Date: August 20, 2017 11:09PM
It's an all metals mode manually ground balanced VLF running at approximately. 4.1 kHz. We still manufacture variants of it for valve & box locating and rebar locating in the industrial line. The platform was developed by a contract engineer Jim Jones (not the bad kool-aid guy) in the mid 1970's.

Re: Fisher 441
Posted by: Doctorcoinz
Date: August 22, 2017 03:32AM
Very good thanks Dave. I am looking for some literature to read about this detector is there anything available on the Internet. I have been unable to find any so far.

Re: Fisher 441
Posted by: Dave J.
Date: August 22, 2017 06:14AM
My bad on the freq., it's 4.5 kHz. Or, maybe the 441 was 4.1 kHz and later variants were 4.5 kHz? I don't know. Been 35 years since I've paid attention to the 441.
http://www.fisherlab.com/industrial/detectors-utility-metal-detectors.htm Our industrial metal detectors are variants of the 441 platform. Manuals are linked on the website.

Just in case I didn't mention it before, the 441 was Fisher's first VLF induction balance metal detector.

Re: Fisher 441
Posted by: Tom_in_CA
Date: August 22, 2017 09:41AM
thanx for the nostalgic look back Dave. I recall that machine. But I didn't see them sell very well. Because at that time, most md'rs were getting the ones with TR disc. on them as an option. Versus that machine which was strictly all metal. So about the only place I could envision using that Fisher would have been on the beach (where you would "ride the knob" when on the wet-salt). Or for nugget hunting. Or some such place where it's not a chore to dig all the iron up. But even then: You could use VLF/TRs, and simply use the all-metal portion of the machine. Thus why have a machine that was strictly all-metal, when you could have both in the same package ? So I never saw that many in actual hands.

Re: Fisher 441
Posted by: Dave J.
Date: August 22, 2017 12:50PM
VLF started with all metals ground balanced operation. For Fisher, that was the 441; several other companies were already doing it. Jones was a contractor, not an employee, and delivered what he was paid to deliver. By then some other companies had VLF discriminators, so Fisher hired Jack Gifford who adapted the 441 platform adding a lot of his own sauce to create the 500 series which offered discrimination. Jack then left, and I was hired in early 1981 to come up with the next advance which was motion discrimination, something White's already had. In 1982 we launched the 1260-X and you probably know most of the history after that.

Re: Fisher 441
Posted by: Tom_in_CA
Date: August 23, 2017 01:18PM
Quote
Dave J.
.... I was hired in early 1981 to come up with the next advance which was motion discrimination, something White's already had. In 1982 we launched the 1260-X .....

I remember the era well. Was only a teen and early 20s at the time. But had started in the all-metal TR days of the mid 1970s. Quickly swept up into TR-discrimination (Ground-hog).

Then one day, about 1978 or 79-ish, we saw some dude swinging a detector like it was a golf club (very fast pendulum swing). We smuggly laughed at how stupid that guy must be. I mean ... duh ... everyone knows you got to creep slow and listen for the whispers, *right* ? Later we began to bump into a few more of these hunters (about 1980 by now). It was the Bounty Hunter SPD and the Whites 6000D series 1. Again, we smuggly giggled at their un-conventional swinging.

Until we began to see their show & tell at the club meetings. Eg.: silver in hand-fuls from parks that we were doing good to get a single silver at per hunt. We quietly went out and bought our own motion discriminators.

Garret and Fisher were late-to-the-game. As you say, it wasn't till 1982-is that Fisher and Garret rolled out their answers to the Whites 6000d. And by then, Whites had the 6000d for about 4 yrs. by then.

In retrospect, the 6000D had a host of downsides (that have since been addressed). But for the era, for certain types hunting (high disc. silver hunting in turfed parks) the 6000d couldn't be touched. Perhaps it could be argued that with reverse discrimination, in moderate soils, that TR disc. could mimic the depth (with less masking), yet the truth was: The 6000D did it 10x faster. Because by their very nature you covered ground faster. Also they handled minerals better in some soils that prior to that had been un-touchable.

In that 4 yrs. or so, it seems that Garrett and Fisher lost a lot of marketing ground. Whites was selling machines like hot-cakes. Even when Garret finally entered the market with the ADSII and ADSIII, it seemed the Whites guys still did better with the original 6000D.

I never much used the 1260x. But recall that it wasn't as deep as the 6000D if I recall.



Edited 1 time(s). Last edit at 08/23/2017 01:18PM by Tom_in_CA.

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Re: Fisher 441
Posted by: Sven
Date: August 24, 2017 08:37PM
My friend bought a 6000D when they first came out. Yup, he swung it like a mad man, always thought he was crazy, I was using Garrett ADS units at the time, always thought he was never going to find anything swinging like that. Wrong he found tons. Shortly after, I got into scuba and started detecting swim holes and beaches, sort of gave up land detecting for 10 years. Finding more and better stuff in the water, lots of virgin water at that point.



Quest Pro & Q40, Nokta Impact
Self built Mirage Pi's --- they work great in trashy areas!!

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