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I have a 1990s era Fisher Gold Bug, the original 19 kHz analog version, long since replaced by newer models. The old 19 kHz model was not particularly hot, but it did have an ability to ground balance out some hot rocks that newer and hotter VLF machines struggle with.

The detector came with a 10" elliptical search coil. I have a couple very rare 3.5" round coils that Fisher made for these models before the little 4" x 6" elliptical replaced it. It's the smallest search coil I've ever owned for a commercially sold metal detector, making the unit into more of a probe than a normal detector.

The threshold was cutting out if the detector was bumped, something loose, so it's been sitting idle for a very long time. I decided it was doing no good as is, and by chance had an opportunity to call Felix at Fisher recently. Felix is another old-timer in the industry like myself, who I have not talked to since I left my old dealership in Alaska over eight years ago. Anyway, since the detector is still actually functional Felix figured they could give it a good refurbish and fix whatever is loose.

The main thing I wanted, however, was to get the detector tuned for the 3.5" coil. Most people do not know it, but analog Gold Bugs are hand tuned for every coil. The coil they ship with is tuned for the detector, or should I say the detector is tuned for the coil. Accessory coils may or may not be a perfect match if the original coil is swapped out for something else. Long story short is I am asking them to match the detector to the 3.5" coil as well as is possible.

The original Gold Bug is a genuine classic. Prior to it, detectors were large square boxes with extremely poor ergonomics. The Bug features a very compact control box that is removeable from a S rod, enabling easy chest or hip mounting. The design seems normal now, but you have to have used what came before to see the genius of what Fisher did with the Gold Bug. 19 kHz was also a radically high frequency at the time, as people were just catching on to the idea that higher frequencies are better for small gold nuggets than the lower frequencies that were the norm of the time. The 19 kHz Gold Bug replaced the 4.5 kHz VLF-660 Mother Lode as Fishers top nugget detector. Frankly, Fisher was not seriously in the game prior to this point, with Garrett probably the leader in VLF gold detectors at the time. A new company named Minelab was just starting to sell detectors in Australia, and had yet to really make a name for themselves.

Anyway, control box and coil boxed up and on the way to El Paso. I'll let you all know how long it takes and what the result is.

Here is a picture of one of the coils. The Gold Bug coils first used a gray dual lead cable, which was replaced very early on with the stouter black cable used to this day. This is the older coil of the two, though it also has less wear. The one I sent in has the heavier cable but is in poor condition. I need to reinforce the coil ears when I get it back since one is cracking. But I decided I wanted to use the coil with the heavier cable, with this older one serving as backup until I sort this all out. And in case anyone is wondering, the old 19 kHz coils do not work on the newer digital versions of the 19 kHz Gold Bug.

fisher-gold-bug-3-inch-round-coil.jpg
3.5" round search coil for original analog Gold Bug

To reiterate what a radical design advancement the Gold Bug was at the time, here is a picture of the detector it replaced, the 4.5 kHz Mother Lode...

fisher-vlf-660-mother-lode-metal-detector.jpg
Fisher VLF-660 Mother Lode metal detector

And the new 19 kHz Gold Bug...

fisher-gold-bug-flyer-1990.jpg

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I bumped into a guy one day at one of our gold areas who was using a GPX 4500 with a 14" Coiltek Elite, it's extremely rare to bump into another prospector in NZ and we had quite the chat.  He was talking about many years ago he had hit this area with his original Gold Bug 19kHz and did very well with it, and I believe him as it's extremely hard to find nuggets there now.  He said he loved that detector and to this day he found the most gold with it than anything else.  I take little notice of that as of course the first detector to go through will get the bulk of the finds but still, it was obviously a great detector at the time.

I love that little coil...  It must look tiny on the detector 🙂

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The 19 kHz Gold Bug was kind of the SD2000 of the day. Prior to it, the best thing going was the 15 kHz Garrett Groundhog circuit. Magazines of the time had many stories of people in Australia cleaning up with these old Gold Bugs. That was, as you note, more a function of being first on the ground, not any magical powers the machine had. It is what I call a "low gain" 19 kHz, not as hot on tiny gold as the new 19 kHz digital models, which are running higher gain circuitry. As I noted, however, this allowed the machine to handle really bad ground relatively well for a VLF detector.

The coil does look tiny. Here is my father using one back around 1990. The coil is described variously as a 3.5" coil or 3-3/4" coil, but it is 3.5" without scuff cover, closer to 3-3/4" with cover. As you can see it is also very thin, especially compared to other coils of the day or even today. Most similar size coils are over twice as thick. Yes, this is a concentric coil, as are all analog Gold Bug coils.

The old coil I am having serviced was used without a scuff cover and is slightly worn through to the epoxy along one edge. The older coil has minimal use and still has the scuff cover on it.

Another note on old Gold Bug models. The earliest are like in the photos below, with a white lower rod as part of the two piece shaft. The coil cables are gray or silver, and did not go to black until later. A three piece rod was offered as an option, and it was so popular it eventually became standard.

FREE BOOK - Advanced Nugget Hunting with the Fisher Gold Bug

bud-herschbach-fisher-gold-bug-1989.jpg
Bud Herschbach with original 19 kHz Fisher Gold Bug

bud-herschbach-fisher-gold-bug-chisana-1989.jpg
Bud Herschbach with original 19 kHz Fisher Gold Bug

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I assume Dave Johnson was still at Fisher (first time around) and had a major hand in the original Gold Bug's design.  How long after it came out before the Gold Bug 2 was released?

Is that gray cable on the coil in your photo actually shielded, double coax??  If so that sure seems weird.  And if not shielded, even weirder!

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Steve,i really do like reading these topics that you post,the images that you also add really complete the story so we can fully understand how these early classic detector and equipment was used.It all makes so much more sense when you can see the images as well.

Bravo,another classic article.

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22 hours ago, GB_Amateur said:

I assume Dave Johnson was still at Fisher (first time around) and had a major hand in the original Gold Bug's design.  How long after it came out before the Gold Bug 2 was released?

Is that gray cable on the coil in your photo actually shielded, double coax??  If so that sure seems weird.  And if not shielded, even weirder!

Dave started with Fisher in 1981 and the Gold Bug came out around 1990. Any detector is a group effort, but Dave is considered the key player on the Gold Bugs. The Gold Bug 2 came out in 1995, and Dave left at about the same time. See the forward in the book below for details.

FREE BOOK - Advanced Nugget Hunting with the Fisher Gold Bug by Pieter Heydelaar & Dave Johnson, Fisher Labs

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That's quite a recounting of history, through the eyes of an icon of metal detector engineering.  Ironically (maybe 'coincidentally' is the better word) I was thinking in literally the last couple days that it would be interesting to read about the milestones of metal detector development.  I think Dave nailed two of them -- ~1974 -- the invention of ground balancing VLF detectors, and ~1981 -- the development of motion all-metal and discrimination techniques.

There are other tidbits in that article, too, such as his statement "The lessons learned from the 1265-X made the later CZ's possible. The 1200 series is gone except for the 1280 Aquanaut which is a specialty nitch item: the CZ platform (originally the CZ-6) is still with us, circuitry almost unchanged 23 years later as the CZ-3d and the CZ-21."  (Steve, I think you've said this or similar here on at least one occasion.  Now we have it from "the horse's mouth.")

As I review my old treasure magazines from 1970 onward, it's an interesting contrast to today's development/innovation.  They went from no ground balancing, no discrimination detectors (BFO's and T/R's) to motion discrimination in about 8 years.  They didn't stop and rest on their laurels then, either.  And it wasn't just one company protecting (with armed guards) patents like they were Fort Knox gold.  It was many companies frantically creating products in competition -- great for the consumer. 

There has been speculation here that Minelab intentionally holds new detectors on the shelf until either competition starts to creap in or they need some extra capital.  Personally I question if they do that, but certainly back from the mid-70's all the way up into the 2000's I doubt anyone dare take such a risk.  "You snooze, you lose."

Thanks for the link, Steve.  (Got anymore?  😁)

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Steve .... Can you do a more detailed review of the Fisher Gold Bug detector with a 3.5 "concentric coil? ... and also a comparative comparison with some other gold detectors? ... on your more mineralized terrain?

I believe that this coil will bring increased sensitivity to very small gold ,,,

I think it would be an interesting topic ..

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Once I get the detector back I'll do something up. But I have used this detector and coil combo before and there are limits to what a small coil can do as far as enhancing small gold capability. The machine itself has inherent limits. However, nobody has compared the original Gold Bug to the modern digital version. Since I just happen to have a new 19 kHz model on hand, I will test them both on tiny nuggets to see just what the difference is. I believe it will be instructive as people tend to focus just on frequency, but there is more to it than that.

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  • Similar Content

    • By Steve Herschbach
      Fisher Research originally released the 19 kHz Gold Bug model about 1987. It was a real breakthrough design at the time with a compact control box, S-rod, and elliptical coils. The detector is a good unit but is strictly all metal (no discrimination). It has no LCD readout and looks much like the current 71 kHz Gold Bug 2 but has a white lower rod and a black control panel face. Some people are confusing this old model with the new so be aware of this when looking at used detectors. The 19 kHz coils for the old Gold Bug will not work on newer versions of the Gold Bug below. The 71 kHz Gold Bug 2 is a totally different detector than the various 19 kHz models described below.
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      ads by Amazon...
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      1987 era analog Fisher Gold Bug
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      Fisher digital Gold Bug
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      Fisher Gold Bug SE
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      Fisher Gold Bug Pro
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      Teknetics G2
      Gold Bug Pro DP compared to Teknetics G2:


      Click on images below for larger versions.....



    • By phrunt
      I finally got out to test out my new 8" X-Coil, I've been wanting a size like this for a long time.  I thought it was going to be impossible to fit the GPZ Super-D design into such a small coil however X-coils after some time have achieved it and it works exceptionally well.  I was running my GPZ in HY Normal with gain of 20, manual ground balance all day.

      My first pellet recovery 🙂

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      Little longish bit.

      0.177 of a gram, my biggest of the day 🙂
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      Off to the edge of this bedrock I got another bit.


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      It was down in that bit of a gap in the rock.



      It was starting to cool down a lot now, well the day was never warm, I guess a maximum of about 5 degrees Celsuis but once the sun starts to go behind the mountains it cools down quickly so I went back to a bit that still had some sun 🙂
      At this point I'd seen the bit of gold and knew where it was sitting down in the gravels but I wanted to show the crazy prickle bush I was dealing with, I'd already broken some branches off at this point, look at them thorns! This video also shows the sideways method I was using to pinpoint.  The center of the coil is definitely it's hottest deepest spot but the edges are still good.
      This was my last bit of the day

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      Once those giant prickle bushes grow in them, they're no longer detectable.

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      It's starting to get very overgrown in places, every year it's getting worse, gradually disappearing.

      Some of these cliff edges would be great to detect and would hold quite a bit of gold I'd imagine but they're just too steep for me.

      This is the sort of stuff JW is chunking away at all day getting gold out of the cracks, he said he's now bought a little battery powered jack hammer type thing to help with the job as it's hard work with a pick, hammer, cold chisel and screw driver but there is a fair bit of gold trapped in the rock.

      It's all in layers and you can smash them out slowly with your pick.

      And my junk for the day, well the junk I didn't lose from my pocket.  So overall I'm very impressed with the 8".  It seemed to me like it was exceeding the GB2 in performance on small pellets at depth.  I'm still better at pinpointing with a small coil like on the GB2 but with practice I'll get better.
      As I was about to leave I went over to see how JW was going, right as I got there he had a target, I took over my GB2 as I know he often uses his one as pin pointer too, especially when smashing out rock as it can save a lot of time.  He was using the nose of the 15x10" coil as his pin pointer and said it was working really well, he found the tip to be pretty sensitive but still too big to get down into the spot well so we used the Gb2 to get narrow down where to smash out... after a fair time of hitting he had the signal out, and it was a bit of gold smaller than my smallest bit and the 15x10" was sounding on it loudly.  He had another signal in the rock to recover so I left him to it as they can take half an hour or more each to get out.
    • By phrunt
      I said I'd never do it, buy a detector that seems about as old as I am for active use, however I did always want to own an old classic.  I was always aiming to get an old Whites from the 80's or so.  The older the better, just to have it in my collection, they're very hard to come by in New Zealand and the only decent one I've found the seller was on the North Island and didn't want to ship it, pickup only.  I wasn't going to fly up to get it.
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      This ability may have been an accident on some units, as more recent Gold Bug 2 models display no change in the disc mode when the threshold control is manipulated. A simple air test between low and high threshold settings while in iron disc mode will reveal if your Gold Bug 2 has this ability to be supercharged."
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    • By N7XW
      So I found this Gold Bug detector for sale.  The owner says it is the GB2 which it appears to be by the housing, but I think it may be an earlier version (?).  Id appreciate if anyone could give me some info on this unit.  In particular, my questions are:
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    • By GB_Amateur
      With the official announcement on May 15 of the (hopefully) mid-summer release of the Garrett Apex there was considerable discussion of the (only) stock coil planned for release and its affects on depth.  Within that discussion Chase gave me incentive to do some testing.  This post is a result of that, but since I think my testing is applicable to more than just the Garrett Apex I'm creating this post in the general DetectorProspector forum.
      The gist of the topic there was how much compromise the 6" (wide) X 11" (tall/high - my choice of word) Apex stock would have on depth.  As I mentioned I have quite a few coils for each of my detectors, but subsequently I realized there was one detector (Fisher Gold Bug Pro) and coil combinations (5" DD round and 5" X 10" DD elliptical) which would best address this issue.  (I also have some other options -- White's TDI SPP and Minelab X-Terra 705 -- but those are a bit less ideal as will be discussed later.  Since I have two other coils for the GB Pro I decided to include those for completeness although they add more variables/concerns and thus don't fit quite as neatly as the other two.
      I initally started with my variable depth test stand which allows me to vary the depth of small targets in 1/2 inch increments from ~ 1" down to 12" depth in the ground.  However, in the midst of that part of the study I realized that I have some (likely iron) trash targets in the field-of-view which compromise the tones/measurements.  Fortunately I also have two cleanly placed buried coins -- a copper alloy Lincoln Memorial USA penny buried at 5" depth and a Jefferson nickel alloy 5 cent piece at 6 inch depth.  Neither of these currently suffers from nearby trash targets.  I subsequently altered my study to use those targets for the coil performance tests.  Unfortunately these also aren't ideal since under the conditions of testing they are too shallow to determine in-ground depth limits.  What I did as a hybrid compromise is to carefully (i.e. measurably, with shims) raise the coil above the ground until the signal disappeared.  For a second (more/less confirmation) test, and one that should be easily repeatable by anyone with the same/similar detector and coils, was to then perform a standard air test.
      Let's start with the conditions of the tests:
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      2) Gold Bug Pro running in "all metal" ("motion all metal" in USA terminology which I like to call minimally filtered), max gain, threshold at 11 (which is about where Kevin Hoagland calls "mosquito buzzing in your ear"), no headphones (so detector's speaker).
      3) My precision for "depth" is 1/2 inch.  That coincidentally was the height of the shims I used in the hybrid test and also my ability to control the hand-held coin distance in the air test.
      4) My determination of (maximum) depth limit was simple.  I increased the depth until I thought I could barely detect an audio signal.  I then decreased the target-->detector distance by 1/2 inch and required that I subsequently heard a clear signal.  If not I reduced the depth/distance and repeated.
      Here are the raw data results.  I'll explain the meaning of the columns shortly.

      You can see the four coils I tested.  The first three are all Fisher manufactured and the last is the NEL Tornado.  Rather than to use the nominal product quoted dimensions ('dim' short for 'dimension' in the column headings) I actually measured the coils and interpolated to account for the fact that a coil doesn't typically have a single extent but rather is a bundle, and further that the bundle obviously fits inside the housing.  For the closed coils this is obviously more vague but in those cases I just used half an inch less than the housing dimension.  An addition oddity is that DD coils aren't really simple ellipses but some overlap of two independent elliptical coils.   'geom mu' is the geometric mean of the two just determined transverse dimensions -- more specifically the square root of their product.  Hopefully you'll see later why I calculated that quantity.  It's not really relevant for the main conclusions I draw.  The last two columns are the actual distances between the target and coil for the limiting distance (see item 4 above).  In the case of the air test that is obvious.  In the 'part ground' test that is the sum of the depth of the coin in the ground and the height of the coil above the ground for both coins.
      At this point I think it's worth discussing some caveats/assumptions/limitations of this test.  Then if you've stayed with me I'll go a bit farther and hypothesize on how to use these data to draw conclusions for other coils.
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      2) With any measurement, there are in particular systematic errors and biases.  I can't "double blind" my method.  That is, I do know which coil I'm testing at a given time and if I have a prejudice for or against a certain coil that could show up in the results.  Also, statistical uncertainties (more succinctly, how repeatable are my data) can contribute to errors.
      It is worth pointing out that swinging the heavy NEL 15" coil effectivly makes taking in-ground measurements with it difficult.  As a result I was unable to confidently get a max depth reading for the penny using that coil, which is why that cell is blank.  No problem with air tests because there, as is standard (?) I mounted the detector in a stationary horizontal position and just 'swung' the targets to determine the (max) limit distances.
      Again, it's really the 5" round DD and 5" x 10" elliptical DD that are most relevant.  The others are include for information purposes but also to add to the plots I show later.  As you can see, in these tests there is a clear and significant advantage for the 5" x 10" elliptical over the 5" round in both the hybrid test and in the air test.
      OK, I now go a bit deeper.  Is there a mathematical relationship which can predict coil depth performance if I know the coil dimensions?  Compared to above this is another leap into the unknown with additional uncertainties.  However, here are a couple plots which seem to indicate relationships between the potential maximum detectable depth and the geometric mean of the coils width and height dimensions.

      (Sorry for the confusion but the Blue dots in both plots are for the 1 cent piece and the red dots are for the 5 cent piece.)  It's better to look first at the 2nd plot -- air test.  There appears to be nearly linear relationship between max depth and the geometric mean of the coil's dimensions, although it appears to trail off with the large (NEL) coil.  Superimpose upon that the effects of ground noise and you see a further deterioration both in absolute depth and also in the trend which is shown in the first plot.  Simply put, it is well known that mineralized ground, even moderately mineralized as in my back yard, negatively affects attainable depth.  The larger the coil, the more ground it "sees", and thus the more ground interferes with performance.
      I'll finish by pointing out that this isn't the first study I've made.  Back 3 years ago when DetectorProspector member Karelian made detailed measurements of a large collection of mono coils on a White's TDI in both ground and air, I noticed the depth vs. geometric mean relationship.  However, without a theoretical (physics/engineering) reason to expect this relationship, at this point it's merely a convenient correlation.  Karelian's data are further muddied by the fact that the coils studied have many manufacturers:  Coiltek, White's, Miner John, Nugget Finder, Minelab,...  I could show those results but I think I'll await the reactions to the above.  I can also do more tests (e.g. with the X-Terra although there is not clean comparison of round vs. eliptical coils with the same width, at least in my collection) or repeat these.  I await your posted reactions (including yawns 😁).
       
    • By Steve Herschbach
      There are three versions of the First Texas 19 kHz circuit for sale at many retailers. One is based on the original Gold Bug Pro model, sold with various coil options, and includes the now discontinued Teknetics G2. There is also a basic Gold Bug version with no manual ground balance, the bottom dollar variant.
      The third version is a later design that added features to the Gold Bug Pro, the result being the Fisher F19. This is now also being sold with various coil options. The F19 is also available under the Teknetics label as the G2+, and now just released under the Bounty Hunter label as the Time Ranger Pro.
      To reiterate, the Gold Bug Pro and G2 versions are the same circuit board, the only difference between the models are coil and rod options plus cosmetic differences.
      The same goes for the F19, F19 Ltd, G2+, and new Time Ranger Pro. The same circuit board with different coil and rod options.
      It is interesting then that the Gold Bug DP, the Gold Bug Pro with 7" x 11" coil sells for $200 more than the more capable Time Ranger Pro. "How can this be," you wonder? The power of name brand and a name, plain and simple. Fisher has a name equated with more expensive detectors, and the Gold Bug name carries it's own cachet. The Bounty Hunter name is usually for lower price models. Welcome to Marketing 101. Based on comparative capability I’d say the Gold Bug Pro is more like a $349 detector these days, so it’s fetching quite a premium.
      Guide To Gold Bug Versions
      Gold Bug Pro / G2 versus F19 / G2+
      click or double click for larger versions....

      Fisher Gold Bug DP and Bounty Hunter Time Ranger Pro

      Gold Bug Pro and Time Ranger Pro features comparison

      Gold Bug Pro and Time Ranger Pro controls
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