Fisher Research Cz-20 Metal Detector
By Andy Sabisch
From Page 42
January, 1995 issue of Lost Treasure

The CZ-20 metal detector operates with the salt-water mode found on the CZ-5/6 active at all times which allows the metal detector to virtually ignore any effect caused by the salt water.

Since the introduction of the 1280-X Aquanaut metal detector in 1985 Fisher Research has been one of the industry leaders in underwater metal detection technology. Building upon the reputation and overall quality of the original Aquanaut metal detector, Fisher has produced other waterproof metal detectors including the 1280-X Wader metal detector and the Impulse metal detector. Their newest addition to this well-respected line-up is the CZ-20 metal detector which was developed at the request of treasure hunters from around the world.


At first glance, the CZ-20 metal detector might appear to be a 1280-X metal detector or an Impulse metal detector since all three share the same control housing. The housing has been time-tested and has an enviable reputation of being both rugged and leak-resistant.

A feature unique to the housings of Fisher's underwater metal detectors is that the battery compartment is physically separated from the electronics section. This ensures that in the event the battery compartment does leak, no water can reach the circuit board and damage the metal detector. The control housing slides easily off the shaft and can be hip mounted in a matter of seconds with the belt clip that comes with the unit.

Featuring an adjustable fiberglass shaft assembly with a comfortable padded handgrip, the CZ-20's length can be varied from 30 to 50 inches. This allows it to be used for land hunting, wading, or even diving without the need to purchase any type of conversion kit. The CZ-20 metal detector can be purchased with your choice of three coil sizes - a 5-inch, 8 inch, or 10.5 inch.

There are advantages and disadvantages to each size; however, in general, the smaller the coil the more sensitive it will be to small targets and the more effective it will be in separating good targets from trash buried nearby. The larger coil is more suited for wreck divers or hunters that desire a slight edge in detection depth over their competition. Consideration should be given as to which coil size is desired as they are not interchangeable.

A design feature of the CZ-20 metal detector that contributes to its exceptional performance in virtually any type of ground is "Fourier Domain Signal Analysis System" which is unique to the CZ family of metal detectors. Transmitting two ground balanced signals at different frequencies simultaneously, more accurate target identification and improved detection depth is achieved even in highly mineralized ground.

The CZ-20 metal detector is controlled through four knobs and a push-button located on the face of the control housing. The VOLUME control also turns the unit on. A feature borrowed from the CZ-5/6 is the audio boost circuit which is activated by turning the volume control above "5." This circuit amplifies weaker signals from smaller or deeper targets while holding the response to larger targets constant.

The DISC control has seven distinct settings which allow the user to select both the level of discrimination to be used as well as the operating mode to search in. Selecting a setting of "0" thru "6" activates the silent search motion discriminate mode with the amount of discrimination determined by the value selected.

A valuable feature of the CZ-20 metal detector is its audio target identification system. Iron objects will produce a low-pitched audio tone; foil, tabs, and most gold rings a medium tone; and coins a high tone thereby allowing users to identify targets with a high degree of accuracy. Placing the knob in the AUTOTUNE position will activate a VLF motion all-metal mode. While this mode does not provide any discrimination, it does give a wide-scan search field with a slight increase in detection depth over the motion-discriminate mode. In areas which do not contain a great deal of trash, this mode would be the preferred search mode.

Turning the SENSITIVITY control fully counterclockwise and listening to the audio signal produced and/or observing the intensity of the LEDs check Battery strength. When searching with the DISC control in the AUTOTUNE position, the SENSITIVITY control is used to adjust the audio threshold heard through the waterproof headphones.

The final knob labeled GROUND is used to precisely compensate for the mineralization present in the search area in conjunction with the PINPOINT pushbutton. Ground balancing, even in areas containing black sand or salt water, is a quick and simple process.

There are preset marks on all of the controls for people that want to start hunting immediately after unpacking the detector.

As mentioned previously, the batteries are contained in a separate compartment located at the rear of the control housing. The factory recommends the use of alkaline batteries for optimum battery life. The CZ-20 can operate for up to 40 hours on a set of four batteries. When re-installing the battery compartment cover, the O-ring and seating surfaces should be carefully inspected to ensure they are clean and undamaged to prevent leakage.

The CZ-20 metal detector comes with a padded and lockable hard-sided carrying case designed to protect the unit when traveling or even simply for storing it between uses.


The first site I took the CZ-20 metal detector to was a small, private beach on a nearby lake. While the beach was never really heavily used, it was secluded which allowed me to hunt it while most of the other beaches were still open for the summer.

Walking to the water's edge, I set the SENSITIVITY control to "5," the VOLUME to "7," and quickly ground balanced the detector. By selecting a DISC setting of "1," iron targets such as bobby pins or berets would be rejected and the medium/high tones could be used to audibly identify the remaining targets. Wading out towards the float, I received a short, high signal. Moving the coil slightly to one side, I pressed the PINPOINT button and criss-crossed the area. The non-motion pinpoint mode combined with the familiar Fisher VCO audio response (the pitch of the signal increases as the center of the coil approaches the target making accurate pinpointing a snap) allowed me to quickly pinpoint the object.

Allowing the sand to sift through the scoop produced two coins - a quarter and a dime. Zigzagging along the beach out to a depth of 2-3 feet, I picked up several more coins and a number of pull-tabs. Most of the coins came from depths of 8 inches or more and showed signs of having been there for some time.

An interesting "quirk" of the CZ-20 metal detector became evident when on several occasions I received both a high and medium tone when sweeping back and forth across what I thought was a single target. In each case upon checking the scoop, I found a coin and a pulltab indicating that the CZ-20 metal detector was identifying each target underneath the coil and allowing the operator to decide whether or not to recover it. If you receive a combination of signals, it is best to check and see what the area might hold as you could be walking away from an exceptional find laying next to a piece of trash!

After hunting the shallow section of the beach for an hour, I walked back to my truck and put on my SCUBA gear. Shortening the shaft all the way, I swam out to the float and dropped to the bottom. With the DISC still set at "1," I planned on ignoring any high signals (coins) and concentrate on recovering only the medium signals (tabs or jewelry). The first dozen or so signals all produced high tones and it was difficult for me to ignore them and continue hunting knowing they were good targets. Finally I received a medium tone and carefully began fanning the sand away with the back of my hand.

At a depth of about 4-5 inches the target broke free and I grabbed a handful of sand from the bottom of the hole. Allowing the sand to sift through my fingers, I saw the tell-tale glint of gold. Placing the ring in my goody-bag, I continued hunting - this time recovering both the high and medium signals. One particular signal that demonstrated the sensitivity of the CZ-20 turned out to be a penny ON EDGE at just over 8 inches.

After 45 minutes I surfaced and swam back to the shore. Emptying my bag I counted out 22 coins, the 10KT girls ring, a silver initial ring, a small earring, two keys, and a few pieces of trash such as tabs and large bolts from the dock. As a side note, the CZ-20 was comfortable to use in the diving configuration and the audio volume was more than adequate to be heard above the noise of the bubbles coming from the regulator.

The next site I took the CZ-20 metal detector to was one of the few Corps of Engineer beaches which could be hunted during the swimming season. Wading out chest-deep, I selected the AUTOTUNE mode and began searching near the ropes. Since the detector responded to all metal objects in this mode, I clicked the DISC knob into the "0" position which activated the audio discriminate circuit to check each signal. After a few attempts, I found this procedure to be quite easy and wound up hunting the remainder of my stay using this method. Despite not having had many people use this particular beach during the summer, I was able to recover a small handful of coins and some pieces of jewelry (unfortunately none of it was gold).

The only "drawback" of the CZ-20 that I found was its extreme detection depth. While everyone asks the manufacturers to produce a deeper-penetrating metal detector, Fisher's engineers seem have taken this request to the extreme. There were a few signals that I was forced to give up on due to their depth. Despite receiving a solid signal initially, when I reached depths of 12 to 14 inches, sand began filling in the hole faster than I could dig it out. Well, I guess one can't complain too much if your metal detector goes deeper than you can dig (I'm already planning on revisiting sites that I thought were worked out!)

While time did not permit me to try out the CZ-20 metal detector at any salt water beaches, I spoke with several treasure hunters who had and they were all favorably impressed with its performance. The CZ-20 metal detector operates with the salt-water mode found on the CZ-5/6 active at all times which allows the metal detector to virtually ignore any effect caused by the salt water. By slightly reducing the sensitivity and sweeping the coil at a normal speed, any chattering is eliminated and even deeply buried targets can be easily identified.


Incorporating all of the features of the field-proven CZ5 and CZ6 metal detectors with the exception of the meter, the CZ-20 metal detector should prove to be an extremely popular detector with not only water and beach hunters, but coin and relic hunters who want a top-notch detector that is totally impervious to the elements. This is truly a detector that will perform equally as well in salt-water surf as it will in a fresh water lake, a schoolyard, or mineralized battlefield or campsite. If you are looking for a single detector that will provide above-average performance in a wide variety of applications, the Fisher CZ-20 metal detector should probably be at the top of your shopping list.

The CZ-20 metal detector comes with the standard Fisher 5-year gold seal warranty, which considering it's an underwater detector, shows how confident the factory is that it will hold up under virtually any condition one might use it in.

For more information on the exciting new CZ-20 metal detector or any of the other fine metal detectors in the Fisher line as well as the name of your nearest authorized dealer, contact the factory at (209) 826-3292 or write them at Dept. LT, 200 W. Willmott Rd., Los Banos, CA 93625 and be sure and mention that you read about the CZ-20 in Lost Treasure.
Author's Note: Due to space limitations, details of land searches made with the CZ-20 metal detector were not included in this article. Since the CZ-20 metal detector shares most of its features with the CZ-5 and 6 metal detectors, readers may want to review Reg Sniff's detailed field tests of these two units which appeared in the March 1992 and March 1993 issues of Lost Treasure for additional tips and information.
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