The Cobra Ii
By Reginald G. Sniff
From Page 46
March, 1994 issue of Lost Treasure
The Cobra II
By Reginald G. Sniff
From page 46 of the March 1994 issue of Lost Treasure magazine.
Copyright 1994, 2001 Lost Treasure, Inc.
Several years ago, Kellyco, a recognized name in the detector hobby, introduced a new detector they named the Cobra. From the beginning, this detector was an instant success. Now, Kellyco has introduced a new generation of Cobra called the Cobra II. This new detector now made by a different manufacturer has many of the same features as the original Cobra but is more stable and more importantly is more sensitive and is less susceptible to falsing.
The Cobra II can best described as an ultra slow motion, very sensitive mid-priced metal detector equipped with the following features and adjustments. It has a conventional sensitivity control, notch and discrimination features, and a three-position mode toggle switch selects between discrimination and a non-motion all metal mode.
The new Cobra deviates from the norm somewhat in the fact that it has an aluminum control housing. This housing and the fact that the detector uses 8 AA batteries make the detector feel a little heavier than some comparably priced models. However, with hip-mounting being very popular, this built in feature seems to all but eliminate any possible weight difference. Operating at a frequency of 12.5 KHz, the detector is ideally suited for the person who wants limited frills and a turn on and go detector. The standard coil is a high-energy 8-inch coil of standard concentric design. An optional 10-inch coil is available.
The discrimination feature of the Cobra II is a little different than found on many detectors. Instead of adjusting the discrimination control to a level and ignoring all targets below that level, the new Cobra II uses a difference in audio tones to distinguish the setting. In other words, if the detector is set to reject pull tabs, all targets having a higher conductivity that pull tabs would have a high tone and pull tabs and other normally rejected targets would respond with a low tone.
One feature that might be very helpful to relic hunters is the feature of the Push-Push control built into the discrimination control. This feature has the ability to accept or reject iron objects while in the discrimination mode. With the iron acceptance on, iron objects will also respond with a low tone.
Where would someone want such a feature? Many relic hunters (and some coin hunters also) operate with the minimum of discrimination, and with the iron acceptance on, the Cobra II can detect most non-ferrous targets with a high tone and the ferrous targets as well as some very deep targets with a low tone. More importantly, good targets located near iron ones may be easier to distinguish.
In areas where all targets may have significant value, a serious hunter could readily search for all targets and know whether it is iron or nonferrous. One such area is in the hunting for gold nuggets.
The variable notch feature does allow the operator to ignore many of the more common trash targets. With the notch on, the discrimination control sets the bottom of the notch zone or region and the notch control adjusts the top. For example, to set a window to ignore targets between a nickel and a copper penny, one would first set the discrimination control to the point where nickels just give a low response. Now a screwcap or a zinc penny is used as a target to set the notch width. By increasing the notch width adjustment to the point where the zinc penny is just rejected, most trash items that fall between screwcaps and pull tabs are readily ignored.
The mode toggle is of a conventional three position design where the center position is the all metal no motion mode, the right position the discrimination mode, and the left is the retune.
The Cobra II has an on board charging system built in that can be easily it would detect the dime. Another target, a nickel buried about 8 inches deep was also easily detected. Considering this target is buried in dry, bare, extremely mineralized ground, I was again impressed.
With the mineralization as severe at my test site as it is, I tried to get sloppy with the detector to see the results. Simply stated, this detector seemed to respond as used when optional ni-cad batteries are installed. The factory recommends the use of a Radio Shack charger and c/3 500 MA or higher nicads.
One other feature that should be noted is, the Cobra II requires headphones equipped with a 1/8 or 3.5 mm stereotype jack.
The assembly of the Cobra II was relatively easy except for the insertion of a couple of washers used as spacers between the coil mounting bracket and the lower stem. These little critters did take a little time to position correctly.
Initial use was as simple as turning on, testing a couple targets for settings of the controls. I mention this because, unfortunately, the discrimination control does not give a hint as to what position or where anything will be rejected or accepted. However, after a couple of minutes of testing, 1 knew the general settings necessary for common targets.
One of the first things I noticed about the Cobra II was how stable the detector was even in noisy environments. On many detectors, turning the sensitivity to maximum results in many false signals. The Cobra II was steady and solid throughout my testing at all sensitivity settings.
At or near maximum sensitivity, the detector responded reliably and positively to all my normal test targets including my 6-1/2 inch deep dime. In fact, I was impressed how have used.
Different sweep speeds were tried and the detector worked well at all reasonable speeds. However, I did find this detector really excelled when I slowed the motion speed down to a nice slow steady pace. With this slow pace, the Cobra II would reach depths equivalent to the best detectors I have used.
Because I like to use the all metal mode a little more than most people, I put this mode through the paces. The all metal mode is also very sensitive.
In fact, it may be a little too sensitive considering there is no ground balance control to compensate for the ground minerals. Over grassy areas, retuning and finding deep targets was easy, but over extremely mineralized bare ground, the extreme sensitivity made operations more difficult. I found I had to hold the coil at a relatively steady height above the ground for best operation.
The iron acceptance in the motion discrimination mode is a feature that I like. However, there is no indication that the feature is on, so the quick way I found to check was to wave my screwdriver normally used for digging over the center of the coil and check both positions of the push-push switch to see if the feature is on.
One might ask why I would like this ferrous mode. Well, I have found that in the dry hot mineralized ground, many good deep targets that would respond correctly if the soil was wet, will respond as a ferrous target many of the times.
A good example of this condition is a penny I buried at a depth of a little over 5 inches. I found this target to be ignored or at best, respond intermittently by the best of detectors when the ground is really dry. With the ferrous feature on, the Cobra II responded with a low tone some of the time and a high tone the rest when passing over the penny.
OUT IN THE FIELD:
The first field testing was done at the local parks. At these sites, the Cobra II responded without a flaw. Sensitivity allowed the digging of several targets over 6 to 7 inches in depth including one nice Mercury dime.
Because like most parks, there was a lot of typical trash (pull tabs, and screw caps), I elected to try a little trick and use the notch and the discrimination control to have the detector ignore all targets below the desired discrimination setting rather than respond with a low tone. To do this, I set the discrimination control to minimum and used the notch control as the discrimination control. With this setup, I set the notch control to reject screwcaps (near maximum). Now targets with less than screwcap conductivity responded with no signal. (The ferrous acceptance has to be off for this setup).
During this phase of testing, I was using the Cobra II like many recreational coin hunters use conventional detectors by ignoring all but the desirable targets. With this setup, the Cobra II was almost too quiet, even at maximum sensitivity setting. In fact, in heavily hunted areas, I would occasionally throw down a coin to make sure the detector was working properly.
After a while with this setup, I elected to readjust the discrimination control so the detector would accept nickels. Almost immediately, I found a couple of the 5-cent coins, indicating most hunters in the area were ignoring them. I did find that the Cobra II also suffered the same fate as all other detectors I have used, that is to respond to some pull tabs and the several of the deeper tab portions of the pull tabs as coins.
The bulk of the rest of the park hunting was typical resulting in a couple of handfuls of newer coins, several wheat backs, the one silver dime, and one junk silver ring. During these outings consisting of a couple of hours of continuous hunting over level ground, the little extra weight of the Cobra II was barely noticeable.
GHOST TOWN HUNTING:
My hunting partner Dan Billings also did ghost town testing. His excursion resulted in the finding of several non-ferrous objects common to ghost towns. Like my tests, the depths of typical coin size targets found were up to 7 to 8 inches in depth.
One problem encountered by Dan was something that led him to believe there was a problem with the detector. This condition was caused by the fact that the coil cable was initially wrapped such that the first wrap went over the top of the lower stem. Also the cable was a little loose near the coil.
When Dan attempted to sweep in tall grass, the detector would respond with what seemed to be a false signal.
What was really happening was the detector was sensitive enough to sense the movement of the coil cable caused by its contact with the grass. The ultimate solution was to wrap the cable differently (starting with the first wrap starting under the shaft) and strapping the cable to the lower stem to minimize the cable movement.
Once the cable situation was resolved, I found the Cobra II detector again to be surprisingly stable even in the trash laden ghost town environment. In fact, this detector did an excellent job of rejecting iron junk, better than many more expensive detectors I have used.
Like the initial testing, the Cobra II seem to respond best and most accurately when the search coil was swept very slowly over the ground. Also, when hunting over really dry ground, raising the coil a little higher than normal resulted in more non-ferrous targets being found than with the coil very close to the ground. Surprisingly, with the coil raised there was no noticeable loss in depth capabilities.
Like Dans testing, I didnt find anything of real consequence. Old bullets and shell casings were common as were parts to watches and clocks. Depths of targets found varied between the surface and 7 to 8 inches in depth.
Kellycos Cobra II is a really top of the line mid-priced detector capable of exceptional depths. This detector is simple in setup and use, yet is complex enough to allow the operator to select and reject different targets. The two-tone audio allows the operator to hear the targets below the desired conductivity setting and make the personal determination of ignoring the target.
The Cobra II is priced at $624.95 but is available to the first 100 buyers for $424.95. For more information or to order, you can contact Kellyco Detector Distributors, 1085 Belle Ave., Winter Springs, FL 32708-2921, or Phone 1-407-699-8700. For information by fax call 1 -407-695-7700.