White's 5900/di Pro
By Jack Reid
From Page 32
November, 1986 issue of Lost Treasure

Field testing the new White's 5900/Di Professional Series metal detector was like renewing an old and trusted friendship.
I've had access to a 6000/Di Series 3 off and on since 1984, and the main difference I found in the two detectors was price. The 5900/Di sells for about $140 less today than the Series 3 did years ago, when it was introduced in 1983. Putting the control boxes of the two detectors side by side reveals identical controls and cali-brations. The meters are also identical, except that the red background of the Series 3 has been changed to blue, which is also true of the other White's Professional Series detectors. In fact, the 27-page instruction book, which comes with the 5900, is titled as being also intended for use with the Series 3.
The 5900/Di is a multi-purpose detector that is particularly well adapted to coinshooting and locating lost jewelry and similar valuables. It offers four search modes: GEB (Ground Exclusion Balance) Normal, GEB Discriminate, TR (Transmitter-Receiver) Discriminate and GEB Maximum. The term TR requires a bit of explanation. Actually, all modern metal detectors operate as transmitter-receivers all the time. TR has come to mean a mode which is not GEB. Someday, the industry might arrive at standardized terms and end this kind of confusion.
A meter (4-1/2 by 2-3/4) is mounted on the handle in such a way that it is always easily visible while searching. The meter performs four functions. A Visual Discrimination Indicator (VDI) shows the probable identity of various targets and it does a remarkably good job of predicting the denomination of various U.S. coins. Another scale is used in all four modes to approximate the depth of coin size targets from one to nine inches. A reference scale shows the target's response in terms of numbers from 0 to 100; passing an object, say an aluminum tab, across the coil during a bench check will show where another will register on the scale. A little experimentation showed that the relationship was very close, even with a tab buried several inches down. Making a chart of where anticipated targets come in on the scale of that particular detector - they're all a little different- can be very helpful in the field. The fourth function of the meter is to show whether or not the batteries are putting out enough power to properly operate the detector.
A trigger switch is mounted to the meter case. Squeezing the trigger toward you performs three functions: regaining threshold sounds after the detector has locked onto the target or any control has been adjusted, changing the operating mode from the selected one by the Mode knob and changing the meter reading from Visual Discrimination to Depth. When the trigger switch is pushed forward, it locks into place the mode and meter changes activated by squeezing it.
The first place I took the 5900/Di Pro was a local park that has been searched so often that at times it looks like the scene of a recent tank battle. Last winter was the worst in many years, and no telling what the heavy rains might have churned up. Moreover, I knew it to be lightly mineralized and thus adaptable to searching at the factory presets (the letter "P" surrounded by a triangle).
With all controls at the "P" positions, the detector is in GEB (Ground Exclusion Balance) DISC., the motion mode. A slow sweep is required to generate a signal. The DISC. knob at "P" is set between "Nails" and "Foil," so a pull tab sounded off with a good, solid beep. The meter, however, revealed these nuisances for what they were. I dug a couple of these - and, sure enough. I also came up with a dime and a quarter, both clad and both correctly identified by the meter. Not very exciting, but encouraging.
There are several large oak trees in the park. Picnickers favor their shade. I chose one at random and began searching just far enough away so that the above ground portions of the roots didn't interfere with swinging the 8" coil I was using. Suddenly, the audio beeped on a target and the meter's usual discrimination scale showed a dime. The needle was far enough away from the "Tabs" area to make it worth digging. Squeezing in on the trigger and holding it' activated the depth scale and shifted the mode from GEB/DISC. to GEB/NORM, a non-motion mode that makes pinpointing much easier than it would be while sweeping in GEB/DISC. Moving the coil around a little showed the shallowest reading needle farthest to the right - to be five inches. The target should now have been directly under the center of the coil, and it was. Depth determination and shifting to a pinpointing mode were both accomplished simply by squeezing in and holding the trigger with the coil remaining directly over the target. No need to raise the coil to fiddle around with any of the knob controls, and then to find the target again.
A little probing around made contact' but at four inches. And it didn't feel like a dime. What could it be?
At first I thought it was a dollar, but closer inspection showed it to be a commemorative coin issued by the city for its 1974 centennial celebration. I immediately laid it on the groundand swung the coil over it back in GEB/DISC. mode. The meter identified it as silver, which since has been confirmed by a jeweler friend. It's a shade larger and heavier than a genuine 19th century cartwheel. It was on its side, which accounts for the meter identifying it as a dime and the discrepancy in depth determination. From its condition, it must have been there since not long after it was issued. How many times had this ground been searched over the years and the coin been missed? Surface erosion during the winter might have helped, but only to the extent of an inch, or at the most two. I was convinced that the 5900/Di Pro is every bit as good as the 6000/Di Series 3.
The "P" positions are a good place to start tuning the 5900/Di. The one exception is the Power control. It quickly became evident that this shouldn't be turned on until after all the other controls are set. Then, turn it all the way right to BAT CK. The meter's needle should swing to the right, to the BAT. GOOD area, just below the depth scale. This does more than just check the condition of the batteries; it shows if the detector is getting enough power to operate properly. If the terminals get dirty or corroded over a period of time or an internal problem in the power supply circuit develops, it won't performeven with fresh batteries. BAT CK will reveal this in no uncertain terms. How many detectors fall to operate properly and end up in a closet gathering dust purely because they aren't getting enough juice, even after the batteries are replaced? No one will ever know.
Then turn the POWER knob to its "P" setting, MAX. This sets the meter for maximum response. The only time MIN should be used is if the meter's response is unstable due to very high ground mineralization, nearby power lines or radio interference.
In 1985, I participated in a coin hunt near Austin, Nev. in which a White's 6000/Di Series 3 was used very successfully ("There's No Help Like Local Help," Lost Treasure, Janunary 1986) and I've had the opportunity to take the 5900/Di Pro to one site where the weather forced us to stop hunting prematurely.
This is GEB/MAX country; strongest signal, Ground Exclusion Balance, but no Discriminator. The valuable coins have been there since before the turn of the century and can be expected to be very deep. White's says that the GEB/MAX signal has about 30% more penetration than in any other mode, and every bit of this is needed. There are few, if any, pull tabs and anything else will be over a 100 years old and likely of some value for that reason alone. But, the soil is highly mineralized and a careful job of ground balancing is a must, otherwise the mineralization becomes part of the signal and will mask some targets. It's quite simple with the 5900/Di Pro.
The GEB knob is used for all modes except TR DISC. MODE which is set to either GEB/NORM or GEB/MAX. I planned to search in GEB/MAX, so I ground balanced in that mode. With all other controls set to "P," hold the detector so that the stem is about parallel to the ground and the coil is waist high. Set the TUNER so that the threshold sound is just audible; it will be very close to the "P" position. Now, lower the loop to the ground. If the sound doesn't change, the detector is ground balanced and you're ready to start searching.
If the sound does change, bring the coil back to walst level and turn GEB slightly left (counterclockwise) if the tone increased, or slightly right, if it decreased. Squeeze and release the trigger switch and lower the loop agaln to the ground and note any change in tone. Keep doing this until there is no change in tone between alr and ground, being sure to squeeze in and release the trigger each time GEB is reset. If you want to search in GEB/DISC., ground balance the 5900/Di in either GEB/NORM or GEB/MAX, then turn the MODE knob to GEB/DISC., and squeeze and release the trigger.
My search yielded what was left of an Indian head penny and some metalic objects that the highly acidified soil had corroded beyond recognition. I think we got all the goodies last year before the weather did us in. What I really wanted to find out was if the 5900/Di Pro would ground balance in the usual way under such conditions, and it did. The penny, such as it was, verified that.
Had I run out of GEB control, there would still have been a way to ground balance the detector. The TR/DISC. mode can be used for ground balancing under extreme conditions. The procedure is the same as in GEB/NORM or GEB/MAX, except that the DISC knob is used in place of GEB. The DISC knob is used in the opposite rotation from the GEB knob. If the tone gets louder as the loop is lowered, DISC is turned clockwise and vice versa. The disadvantage of doing this is that TR/DISC doesn't have the penetration that GEB/MAX does and that DISC can't be used to ground balance and to reject junk at the same time. Nevertheless, this is very unlikely. The chances are that if the detector won't ground balance, it's over some metal and moving a short distance away will solve the problem.
The DISC. knob is used to adjust discrimination in the two DISC. modes. It affects the audio, not the meter, and permits the operator to set the detector to distinguish between desirable and undesirable targets. The audio responses of targets above the DISC set point produce louder tones. Targets below the set point produce softer or broken tones, or a complete dropout. I had some difficulty in distinguishing between nickles and tabs in a bench check, but this is a universal problem in coinshooting. The responses of the two items are very close and tabs - some in a variety of sizes and shapes - are often broken or distorted in use.
The meter and the trigger switch, mounted to it, come into play once the instrument sounds off on a target.
The VDI scale indicates its probable composition, starting with iron at the far left and working up through foil, tabs, gold and silver to the far right. It also shows the probable denomination of coin size targets in terms of U.S. coins.
Once the probable nature of the target has been identified, squeezing the trigger accomplishes two things to pinpoint its location:
A) It changes the meter over to read depth in inches from one to nine. This is very helpful in avoiding damage to the target with your probe.
B) It changes the mode from the one set by the MODE knob. For example, GEB/DISC is the primary search mode for coins in a junk laden area. But, the coil has to be in motion to generate a signal. This makes pinpointing difficult. Squeezing the trigger shifts to GEB/NORM, which is non-motion, making pinpointing much easier. A schedule of mode changes is shown in the instruction book.
All in all, the 5900/Di Pro operated every bit as well as its popular predecessor, the 6000/Di Series 3, which makes it one fine metal detector and, considering its moderate price, a tremendous value.
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