Considering A Fisher Gold Bug Or Other Detector

[Ham]

My specific interest is detecting gold jewelry at the beach. This would be in one foot of salt water, salt water sand & dry sand. I was considering a used (19 khz) fisher gold bug. Which model gold bug would you suggest? Maybe there is a preferable detector for my specific use?

 

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[cudamark]

A Gold Bug will work but keep in mind that it isn't waterproof and it will pick up the tiniest little piece of junk as a good target. I would recommend a dedicated water machine. If you want discrimination, an Excalibur is hard to beat for salt water. A CTX3030 also works great but is more money. If your area is relatively iron free, a waterproof P.I. machine will also work fine but it also will sound off on every piece of junk metal too. If you're careful and only hunting shallow water, just about any Minelab machine will work great on a salt water beach. Another good choice is the Fisher CZ21.

 

[Terry Soloman]

My specific interest is detecting gold jewelry at the beach. This would be in one foot of salt water, salt water sand & dry sand. I was considering a used (19 khz) fisher gold bug. Which model gold bug would you suggest? Maybe there is a preferable detector for my specific use?

A "VLF" or very low frequency type metal detector (like a Fisher Goldbug),works extremely well on dry sand and in fresh water. It does not work as well in saltwater, or on wet ocean-water beaches. In highly conductive saltwater conditions pulse induction or "PI," and multi-frequency VLF "BBS" metal detectors excel.

The VLF metal detector sends 4,000 - 80,000 radio waves per-second into the ground. When the radio waves hit something conductive - like an iron nail, gold ring, coin or aluminum pull-tab, a magnetic field sets up around the object and a particular signal frequency is transmitted back to the detector's receiving coil. VLF metal detectors have the ability to "discriminate," or tell what type of metal they are seeing by "reading" the return signal frequency.

Radio or "sine" waves bounce off everything that is conductive in the sand or water. This is why VLF detectors must be "ground balanced" to work effectively in highly mineralized soil, or on highly conductive saltwater beaches. You must tune or adjust the machine to see through the "fog," or white-noise created by the salt and iron in the sand or water you are detecting. Unfortunately, this usually leads to a loss of depth and stability with most VLF detectors.

The Minelab Excalibur uses Broad Band Spectrum, or “BBS” technology (multi-frequency), and retails for about $1,500.00. According to Minelab, their BBS operating system, “simultaneously transmits, receives and analyses a broad band of multiple frequencies to deliver substantial detection depth, high sensitivity and accurate discrimination for a wide range of target types.” The key takeaway here is “multiple frequencies.” Unfortunately, radio waves regardless of their frequency still have to be filtered and balanced in heavily conductive wet-ocean sand and highly mineralized saltwater. That limits the systems depth capabilities.

The magnetic iron sands (“Black Sands”), salt, and high concentrations of other minerals in the water and sand conspire to bounce the radio waves away from the target. Conductivity and mineralization act like a shield around the target and create white noise that must be filtered electronically. Think of it as turning on your bright headlights in a heavy fog at night. All that powerful light is diffused and causes a complete white out – you can’t see anything three-feet past the hood of your car! However when you turn on your yellow fog lights, you can see a little further – not as far as you could in clear daylight, but further. That is why all radio wave machines must be “ground balanced” or tuned, to maximize their depth potential, and why BBS filters and multi-frequencies are so effective – yet still limited.

Unlike BBS and VLF metal detectors which constantly send and receive thousands of low frequency radio waves per second, a Pulse Induction (PI) metal detector fires high-voltage pulses into the sand several hundred times per second. If no metal is present the electric pulse decays at a uniform rate with no anomalies. When metal is present a small “eddy” current flows through it causing the voltage decay time to increase, which creates a measurable anomaly. Unlike VLF radio waves, electronic pulses are impervious to the effects of conductivity and mineralization, and are unaffected by salt or black sands.

Using the same heavy fog at night metaphor that I referred to earlier, pulse induction is like headlights that cut completely through the fog as if it were not there at all. The trade-off for that added depth and clarity is the inability to discriminate, or block out iron targets that you generally don’t want to waste time and energy digging. While a pulse induction machine detects all metals without discrimination, the minute differences in the signal tone and quality can give a skilled and experienced operator a clue as to what the target may, or may not be.

So basically, a Fisher Goldbug may false and chatter in the wet sand and salt water.

 

[Ham]

Is 19 khz the optimum frequency for hunting gold jewelry?

 

[Sandman]

Is 19 khz the optimum frequency for hunting gold jewelry?

NO...It is more important not to Disc it out. If detector sounds off on a pull tab it will sound off on 90% of gold rings. The other 10% will be in the foil range.

 

[DDancer]

Hrm, I've seen plenty of reports of people using goldbugs reliably on the beach~ however as stated somewhat they are not very effective in wet sand due to salt conductivity nor are they waterproof. Frequency is a consideration however you would be best served with a detector that is built for beach conditions. PI's are effective but also effectively will give you zero discrimination and will pick up the smallest bits of metal at some pretty impressive *and tiring* depths. The goldbug will pick up all metals too; however you'll find yourself constantly ground balancing and have plenty of falsing as mineral and salt conditions change quite dramatically in beach sands.
Ask around a bit in the beach forum and check out their threads. There may be an inexpensive machine that suits your needs that they can point you to.

Terry~ sorry I'm going to have to agree to disagree with some of what your saying. VLF's regardless of frequency measure the change in the em field they set up around the coil to determine conductivity of a target passing thru the field, a distortion. Some metals react more to certain frequencies than to others causing greater distortion of the field. Ground balancing essentially is just calibration of the em field to null out the distortion effects of mineralization/salts and other factors to create a balanced field. Depth and sensitivity are limited by ground balance due to the level of distortion created by the ground~ higher minerals and salts= higher conductivity, lower is lower~ this level affects the receiver circuits acceptance level for valid targets to be reported.
Example: The mineral/salts on a beach have a conductivity level equal to a silver dime, the target gold ring has a level equal to a zinc penny, the detector will not recognize the ring because it does not meet the ground balance threshold of a silver dime.
I'm not ignoring depth in the example: it plays a factor too however I'm just stating a simple example of how GB affects target reporting.
Depth is affected by GB in that the threshold for target reporting is also an imaginary line under the soil where the detector senses and adjusts to the greatest distortion caused by ground conditions. IE: the silver dime threshold is 4 inches down so anything below that that is not a silver dime will not sound off, above that depth will sound off~ however this effect is somewhat proportional depth wise in that at 5 inches only a quarter will sound off and at 6 only a half dollar ect... ect... till no detection will occur as the detector no longer sees a distortion relative to GB.

PI's are not immune to mineralization or salts. They are affected, however its to a much lesser degree, because their ground balancing is a cancelling of the reactivity of the soil. PI's as stated send out a pulse of energy that in turn excites the ground and any metals and salts in it. During ground balancing the detector reads this excitatation, the decay of the eddy currents induced by the pulse, and subtracts it from the return signal. Metalics and salts have much longer decay fields and as a result are picked up by the detector *after the GB subtraction* as targets. These effects by salts and minerals are not really seen in modern PI's that feature automatic GB~ but I can tell ya they are pretty pronounced in manual GB PI's. GB on PI's affects sensitivity and depth as well but because the technique for detection is so robust you can get incredible depth even in very hot (conductive) conditons. The depth you get for any target of any size will be determined by how large the target is and how long it takes for its decay signal to drop off relative to the grounds decay signal. Because salts have to be very concentrated to produce large effects most PI's are relatively unaffected by beach conditions.

My thoughts.

 

[Terry Soloman]

...Terry~ sorry I'm going to have to agree to disagree with some of what your saying...

...Because salts have to be very concentrated to produce large effects most PI's are relatively unaffected by beach conditions....

It's all good. What I wrote is intended to be as simple as possible for a newbie to understand that a VLF like the Goldbug, is not the first choice for hunting gold on a saltwater beach. I think we agree that a multi-frequency VLF or a pulse induction beach machine is the way to go in a saltwater setting.

 

[cudamark]

I think that's what I said too.....just without the science lesson!

 

[CincinnatiKid]

Good machine, but I advise against using on the beach. In any amount of water. One slip of the handle and it's over.
GL
Peace

 

[DDancer]

Agreed Class over cuda hehh. Still the gold bug will work... just not as hot as one would think. No machine just gets the gold... gotta get the junk or its just not fair to the rest of us, no? *grin*

 

[SouthFLdigger]

I have a Teknetics G2 latest model, ground balances fine with zero chatter in salty wet sand where the waves crash. However as everyone above stated, the depth will suffer i get about 7-8 inches on a pulltab at best in salt water drenched sand running 100% sensitivity. My CZ20 goes about 10 inches, get a PI or a multi-frequency machine (CZ-20, Excalibur..). Oh salt spray is also a hell of a thing, it has a way of working its way in through the turn knobs and any other non sealed area working its way to the electronics.

 

[Olegrumpy]

I have a Teknetics G2 latest model, ground balances fine with zero chatter in salty wet sand where the waves crash. However as everyone above stated, the depth will suffer i get about 7-8 inches on a pulltab at best in salt water drenched sand running 100% sensitivity. My CZ20 goes about 10 inches, get a PI or a multi-frequency machine (CZ-20, Excalibur..). Oh salt spray is also a hell of a thing, it has a way of working its way in through the turn knobs and any other non sealed area working its way to the electronics.

I have been using the Goldbug Pro at the beach, to my entire satisfaction.

The best combo I have for wet sand, or damp sand (high tide mark) is fitted with the 5" DD coil.

In air tests, with the Ground Balance factory setting (82.9), the Goldbug + 5" DD detects a small (7gr) 18 K gold chain at 6+".

When you set the ground balance to fit salt water (0), it barely detects it at 1".

The trick, with the 5" DD coil, is that it will suffer much less from ground conditions (and salt) due to the smaller amount of ground it has to handle. So I try to keep the factory set ground balance as long as possible, and when it becomes chatty, the first thing I will lower is the sensitivity.

When this too becomes unsufficient, I will gradually lower the ground balance as to maintain good sensibility to gold. NOT immediately balancing to salt water.

In 20 years of intensive beach hunting, I discovered that "following the rules", (and mainly setting an exact ground balance to match sand conditions) will result in problems in finding micro jewellery.

So, be creative, use the right equipment (smaller DD coil) and the right settings, and the GoldBug will find you the good stuff !

HH

Grumpy.