100 khz detectors

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Compass Yukon series,77b,77b automatic,94b,judge,judge2 etc. I believe were all 100khz detectors. Some of them were made as hipmount which would really look good hunting on a farm not to mention light on the swing.

[Tim]

I have a 94b and a Judge5. The 94b is slightly more sensitive to gold, but the Judge5 ignores iron slightly better. 94b is a very simple one-sided, single board. It is small, simple, and very light. If I were to mod/re-manufacture either, a more sensitive handgrip-mounted tuning pot would be a benefit. This is affected by ground effect. The 94b auto may have overcome this problem somewhat. The Judge 5 is a 2 board design. It is slightly simpler than the Judge 1/2, which has auto-tune, but the Judge 5 does not.
My 94b will air test small gold nearly the same distance as my GMT, though the signal isn't a s loud. For trashy areas where the GMT is un-useable, the 94b excels. Mineralised ground reduces its depth, but still a very respectable machine, even by todays standards. I've never been one for bells, whistles, or meters. That being said, the GMT-E series black sand meter is a invaluable panners accompaniment, and puts you in the zone.
I think I read on Compass forum that the Judge is 5.5kHz(??)
The 77b apparently is the ducks guts of the early Compass's.
The fact that there is a whole forum dedicated to these detectors is an indication of their popularity.

[Dave J.]

The old fashioned approx. 100 kHz "TR" machines detected the reactive phase signal, they didn't work like so-called VLF's. VLF's had far more depth and thus displaced the TR's in the market. However when it comes to seeing nonferrous through iron metal on a trashy site where depth is not a criterion, a good TR will beat any VLF.

[Koala]

Original post was about using s higher frequency to ignore the iron.

I don't see any difference at all between a 6 or 14 khz machines.

What does make a difference is coil type and size.

A large coil is no good in field that use to have wooden pig pens in them. When you have over 10 rusty forged nails per square metre there is just too many under a large coil.

Regardless of what you see on YouTube nail coin nail coin nail beeping over the coins. This is not what happens in the fields. The coins are rarely exactly flats and the nails are rusty and leeched into the ground. Giving the iron a much bigger response ratio than the target.

Best I can do with any machine is 1/2 the coil diameter.

Air testing I find little difference between a concentric and a DD. DD Is better when the nail is close to the surface and the coil is run down the nail. Turn the nail through 90 degrees and the results are reversed.

However in a real field I find the concentric slightly better.

Less pops and cracks means I am able to run less discrimination and pinpointing is better. Great on an infested site.

[Qiaozhi]

Original post was about using s higher frequency to ignore the iron.

I don't see any difference at all between a 6 or 14 khz machines.

What does make a difference is coil type and size.

A large coil is no good in field that use to have wooden pig pens in them. When you have over 10 rusty forged nails per square metre there is just too many under a large coil.

Regardless of what you see on YouTube nail coin nail coin nail beeping over the coins. This is not what happens in the fields. The coins are rarely exactly flats and the nails are rusty and leeched into the ground. Giving the iron a much bigger response ratio than the target.

Best I can do with any machine is 1/2 the coil diameter.

Air testing I find little difference between a concentric and a DD. DD Is better when the nail is close to the surface and the coil is run down the nail. Turn the nail through 90 degrees and the results are reversed.

However in a real field I find the concentric slightly better.

Less pops and cracks means I am able to run less discrimination and pinpointing is better. Great on an infested site.

This exactly what I've found as well.

[Tim]

The area I live in here in the UK has minimal levels of ground mineralisation. Centuries of activity on the land does often mean that the iron infestation can be a problem.
Back in the 70's I did pretty well with the old 100Khz machines of the day and I would like to have another go with one.

There are plenty of vintage detectors of that era about but determining what frequency they work on is causing me problems. That information seams to have been rarely published.


I think what I may need is a 100Khz machine with disc and some sort of ground control and a press button retune. A meter would be nice but isn't essential as the general rule on the farm land I search is - if it isn't iron, then dig!
Something not too heavy would save my old bones, but if that is too much to ask, so be it. If memory serves me, most were heavy in those days!

Perhaps one of the last of the 100 khz detectors, although I know some of the old classics take some beating from what I've heard.

I would really appreciate suggestions of make and model numbers to help me track one down.
Thanks in advance!

100kHz, Button reset, ground balance- Maybe Compass 94b auto, 99b, 77b auto. And some of the Judge series(think these are 5.5kHz though).
The Judge series may have better depth than the 100kHz. They also have a discriminate knob that can dial out bottle caps and other iron composite metals.
They don't call these things "iron killers"for nothing.