CZ-21 Air Test Results, lets see some CZ-20 data

I did some air tests on my new CZ-21 (8" coil) with a factory quality certification dated 8/13/09. I, and I'm sure others, would like see some similar testing done on a CZ-20 for comparison. Any volunteers?

I went out to a local park and set-up an all plastic bucket upside down and set the coil on top of that at about 18" off the ground. I tested a few different coins in two different modes, auto tune and disc "0" using a plastic nugget scoop to hold the coins. For the auto tune I adjusted the sensitivity to the threshold of my hearing.

Here are the results:
Quarter clad 9"/14" (disc 0 / auto tune)
Dime Clad 8+"/13+"
Dime silver 8+"/13+"
Nickel 7"/10"

I should note that in the auto tune mode I only recorded the distance that was easily discernible even though there was a slight hint of a target at greater depths. I don't feel I would have picked it up in a real world situation, I'm sure there are some hard core nugget hunters out there that could.

Joe



Edited 2 time(s). Last edit at 08/05/2010 02:27AM by Joe.

will do the same test as soon as i can!

Thanks Seeker!



Edited 1 time(s). Last edit at 08/05/2010 02:02AM by Joe.

I can air test my CZ20, but it has the 10.5 inch coil on it.

therover61 Wrote:
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> I can air test my CZ20, but it has the 10.5 inch
> coil on it.


Actually, it would be great to have that info too. Maybe if theres someone out there with a CZ-21 that has a 10.5 willing to do the test we could cover all the bases.

Joe,

There is a disparity/problem with your ID mode. The auto-tune (all-metal) mode is correct numbers/depth. 13"+ on a dime with 8" coil is correct. The ID mode should ascertain approx. 12" on a dime with 8" coil. I'm glad.............that............at least ONE of your modes ..functions properly. It is my deepest recommendation to hunt in the auto-tune (all metal) mode..... for obvious reasons. I still have GREAT CONCERN about the performance of the CZ-21's.

I have several CZ's (imagine that)...........and all of them......whilst in 'salt' mode.... will ascertain a dime at approx. 12" in the ID mode.... and greater depths in the auto-tune mode. This is with 8" coils. (Add approx 1.5" - 2.0" additional depth when 10.5" coil is installed).

CRITICAL, CRITICAL, CRITICAL. Let's see if folks can start to understand.....and pick up on something here. A nickel is more than double the mass/size of a clad dime; YET, look at Joe's results posted above. WHAT DO YOU SEE!!!!!!!!!!!!!!!?????????????????

....so the detectability of a given object is more directly related to the conductivity than mass?

Conductivity AND mass matter. BUT......when one of the two is presenting a 'detectability' hard time........your performance; subsequently end 'results' will suffer.

Tom, I do not own a CZ-21, however is the disparity in the detection depth of Joe's nickel test , "with greater probability", possibly due to a problem with the coil. ( I believe the 21 is dual freq. 5 & 15 khz) ? And/or an impedance mismatch?, I do know IRT RF max. power is always TX/RX if impedence is matched exactly. Or is this simply the CZ21 depth questions you have concerns about?

I understood it to mean something to the effect of conductivity X mass = signal strength.

No problems with coil. No problems with impedance. Yes, 5 & 15 Khz. Most beach detectors are gold-dead.........as can be seen with this nickel result. A clad dime is 2.27 grams. A nickel is 5.00 grams......... More than double the mass of a clad dime.............yet, quite a bit less detectable. A nickel is a fairly low conductor. Gold rings are even lower in conductance. And most gold rings are not 5.00 grams. A woman's gold engagement ring is usually one or two grams.....and about the diameter of a nickel.....or smaller. And a nickel has a lot of surface area......and does not sink too fast. A gold engagement ring has a big hole in the middle...posing minimal surface area.....is high density/heavy; subsequently, will sink much faster. Starting to paint a picture?????


Yes, conductivity and mass play a large role in detection depth.

OK....just got done air testing in the back yard. Had the CZ20 with 10.5, Shadow X3 with 7 inch coil, and Baron Millenium Cointrax II with 10 inch coil.

The CZ20 was set up with Vol-10, Sen 5-6 ( I cannot run my CZ0 higher than that sensitivity level without it starting to false occasionally. However, I did run the coins pass the coil at sen 10 when there was silence and got at least 1-2 inches more depth...BUT, it just falses too much ) , GB 5.

The Shadows settings were Sens - 8, disc - 1

CTII was set with sens at 4 ( which is about 2/3) 10 being lowest, 1 being highest in both disc and all metal

The coins were the same as what Joe used. Q, D, N, Silver D

Results of CZ20

Quarter clad 11"/14" (disc 0 / auto tune)
Dime Clad 9"/11"
Dime silver 9"/11"
Nickel 8"/10" The nickel sounded at high tone up until 6 inches, then it went mid tone/ high tone from 6-8

Results of the Shadow ( remember....7 inch coil)

Discriminate was set at the lowest setting since there isn't really an all metal mode

Quarter clad 8 1/2"
Dime Clad 7"
Dime silver 7"
Nickel 9 "

Cointrax ( I recorded the depth in discriminate up to the point where the LED continued to read anything other than iron)

Quarter clad 11 1/2"/13" (disc / all metal)
Dime Clad 10"/11"
Dime silver 10"/11"
Nickel 11 1/2"/13 1/2"

Yup....my CTII is probably my deepest nickel finder. The cool thing about that machine is you can set a break point in all metal where certain conductive targets (like iron ) gives off a stacatto like tone ( like bap,bap,bap,bap,bap...machine gun like) where anything about that gives off a beep/whap sound. All coins in the all metal mode did not at any point have the stacatto sound.

On the CZ-20..........whilst in auto-tune (all-metal) mode............your Sens must be on '10' and volume on '10'. You will have a threshold hum........but this should prove fairly stable (with 'some' quivering). If you run your Sens on '6' whilst in auto-tune......performance results will be substantially reduced. You must at least ascertain a bit of a threshold hum.

The CoinTrax may be the deepest on the nickel..............until you expose that unit to the wet salt!

Good report.

I see, so you are simply saying "that's just the way it is" IRT VLF'S and his detection depths for the nickel are normal, (for the air test) , I am sorry, I was under the impression something mechanically/electronically was wrong with the CZ21.(as you made ref. to concerns about the cz21 depth.....[www.dankowskidetectors.com]) Hence the need for the PI with the short pulse delay (8-10 uSec) to detect metals with lower conductivity in wet salt or higher VLF frequencies in dry mineralized soil. Sorry for my confusion.
Tri

When I did my air tests the sensitivity was set between 7 and 8. I did lower it just to see what would happen and that brought it down to around where therover61's depth was, although I didn't record it so I'm not sure of the exact number's, I'll get out and record it with his settings when I get a chance. When I pushed it up to 10 it was impossible to hear anything other than a constant, loud, hum.
I've read and watched allot of nugget hunting books and DVDs and they all say your threshold needs to be set at the point at which it goes from nothing at all to just starting to hear the humming, other wise you won't hear very small or very deep targets. In the auto-tune mode set like this I can hear a 3 grain (not gram) gold nugget at a whopping 3/4" with my CZ-21, sensitivity at 5 and indoors.



Edited 3 time(s). Last edit at 08/07/2010 03:50AM by Joe.

And no, I don't plan on using my CZ-21 for nugget hunting, It was just a FYI thing.

I do believe that I need to clarify myself. The disparity/differential between the ID mode and the auto-tune mode is too great.....on Joe's CZ-21. The ID mode performance is quite sub-par. Detector calibration problem. xxx The all-metal/auto-tune mode is nominal.

There is another problem that has nothing to do with Joe's detector; rather, a overall/aggegrate problem inherent to VLF IB units. When set up for wet salt beaches........these units are quite gold-dead. In an air-test, , , , and not in the 'salt' mode......they perform much better with gold. This is far from real-world conditions. Hence, my comments about PI detectors with very short pulse delays for the wet salt..........opening the door to a world that is 'unknown' to nearly all beach detectorists.

Tom,

The sensitivity was set at 10 and volume at 10 when testing the CZ20 in auto tune.

You are absolutely correct about the Cointrax and wet, salt sand. I cannot ground balance it on the wet salt sand and it will not run there. I may still be a little new to the machine and not familiar with how to override the automatic ground balance ( but I think I did it correctly) and even when doing that, the CTII can't run smooth on the wet, salt sand. At least not with the settings I had it on. I also had the bigger coil on it when I tried, so maybe the smaller coil will be a little less noisy.

Since I have a lot of other beach machines, I did not try to pursue it. At some point I may take it back to the beach and adjust the sensitivity and discrimination settings to see how it reacts.

It does run perfect on the dry sand though, and that is where I use it to search for the gold. It's my number one dry sand machine. However, I just purchased a new Gold Bug that will be coming early next week, and plan on taking it to the beach on vacation for some testing and usage. It went back to FT for the adjustments needed on the GB and trimmer, and reports on the other forums state that after that adjustment, everything runs great and the unit is a good one. As always, can't tell until I use it, but since it's light weight and has some features I like, if it can run smooth on the wet, salt sand then it will be a keeper.

I think I am going to do the same tests using my CZ6a with 10.5 in normal vs salt mode, as well as my DFX. I know they are only air tests, but it's fun. Won't test my PI's ( Goldquest and HH PI ) since air testing is useless on them. I already did it before and realized they hit nickels and gold WAY deeper in the ground than in the air. Especially in the wet sand and suds.



Edited 1 time(s). Last edit at 08/07/2010 01:21PM by therover61.

Tom, Much gratitude for breaking it all down.......You are the "CONSUMER REPORTS " of the metal detecting world.......I am truly surprised you don't have a television show...........maybe one in the works.......?............Since they already have American Pickers.......lets see....AMERICAN DIGGERS.....!!

PS Seriously, your following is already legendary.
Thanks again Tri

therover61 Wrote:
-------------------------------------------------------

> I think I am going to do the same tests using my
> CZ6a with 10.5 in normal vs salt mode, as well as
> my DFX. I know they are only air tests, but it's
> fun.

Really looking forward to seeing these result!

Tri.....thanks. I need to finish a Beach Hunting DVD before proceeding to the next endeavour.

TR61..........a thought for you. I have a White's MXT that runs very stable in the wet salt. Nice and stable. But...........it'll only detect a nickel in the wet salt at just a few inches deep. Lower conductors (and less mass) like gold rings......to even less depths. Moral of the story: Nice-and-stable/stability might not have merit.

On this same subject......................this MXT has a 950 (9.5" concentric/round) coil. At a famous/producing relic site.......littered with square nails..........the MXT is very stable & silent in this carpet of nails. Very, very, very stable/silent. TOO silent!!!! xxxxxxx Moral of the story: It's so 'silent' that it will not unmask non-ferrous relics in close proximity to iron square nails. WHEREAS the F75 is NOT silent/stable..........rather..........it's quite noisy.......but will unmask MANY non-ferrous targets in a carpet of nails. xxxxx

* There is no 'fatigue' factor whilst hunting with silent MXT. When going home after using MXT......there is 'fatigue' factor due to NOT finding relics. xxxxxx
* With the F75...........there is brain/ear 'fatigue' whilst hunting with this noisy detector. When going home after using F75..........there is no 'fatigue' due to finding a pocket full of relics.......equating to a satisfying level of success. . . . . challenging as it may be.

((( Not sure if this (potentially) abstract thinking makes any sense ))).

Tom...I "pontentially" understand...at least in an "abstract" way...(I do hope I'm learing something)...when a given unit has been adjusted for proper threshold "hum" my interpretation is that it is only then...in this somewhat "unstable" mode that you can begin to realize the detectors "true" performance. Even only slightly adjusting this level to mute this annoying chatter will render targets silent and/or "dead" to the detector. It is similiar to the approach of running at the very least with 0 discrimination so that you hear EVERYTHING. As you have said on previous occassions...and on your DVD...you want to know 100% what is in the ground 100% of the time. So do I. I may not dig EVERYTHING but at least I have an opportunity to do so if I please.

Am I learning anything? Feel free to set me straight if I'm straying of the path of understanding.

Running the threshold just below a light hum..................where it is 'just barely' quiet...........does not render all targets undetectable. Only the deepest/weakest targets may be missed. Running the threshold just barely into a very mild audio 'hum'........and you are at max/nearly max performance.

The CZ has a unique characteristic whereby... setting Sens on around 4.8...gives you max depth performance whilst in ID mode. Simply switching over to the auto-tune (all metal) mode...........and leaving Sens on 4.8.....is a big mistake............. about 1/2 of the depth performance is lost. Increasing the Sens to a very mild threshold 'hum' is paramount. This holds true for nearly all CZ's. The CZ-20 max depth Sens setting in ID mode is approx 5.8.

In the ID mode............Sens is a NON-linear scaling/function.
In the all-metal/auto-tune mode................Sens is a fairly linear function.

Is the 5.8 for the CZ-20 rather than the 4.8 for other CZ's have anything to do with it being locked in salt mode?

No...........it's just how that unit is set up.

And................as far as the digital CZ's...........a Sens setting of '4' ...and you have about 98% of it's max depth performance. A setting of '6'......and it's all in. This is for ID mode only. In the auto-tune/all-metal mode.........once again........a threshold hum is required for max depth performance.....and this is usually with a Sens setting of '10'.

I've been asking around on other forums and one poster stated he's had a few 20's and 21's and one of his 20's really stood out for depth until he sent it back (for a forth time) to be repaired and now it's depth is like all the others and his ground balance has to always be set at 10. I know having employees train employees results in the xerox effect, a copy of a copy of a copy loses detail with every step, but I didn't pay for a copy of a copy! How come they can tune a CZ3D but they can't tune a CZ-21? Is there that much difference in the process?

In all fairness to Fisher, the wise thing for me to have done would've been to call them before buying my detector and ask what the minimum depth it would air test at under warranty. Then decide whether I could live with it. I decided to call this morning instead.
First off, no stupid machines, I got a person right away and everyone was polite and tried to be as helpful as possible. I asked about the depth under warranty and was told a dime over an 8" coil should get about 9+ inches in discrimination mode "0" with max sensitivity and 10-11 inches in auto-tune. He said they'd be happy to recalibrate it for me if I wanted to send it in.
I'm on the fence as to whether or not I want to send my detector in. I don't know if I want to risk loosing 3" of auto-tune to get 1" of discrimination. I still have 23 months to decide so I'll get out and use it for awhile first.
I wanted to ask someone at Minelab the same thing about the Excalibur but after four attempts and still no tech to talk to I gave up.



Edited 1 time(s). Last edit at 08/09/2010 06:39PM by Joe.

I want to thank Minelab for helping me feel good about my decision to get a CZ-21. After several more attempts to speak to a technician I was transfered to someone in management and was told "there's no one here that can answer technical questions but I can put you in touch with one of our dealers".
The Excalibur may or may not have an edge over the Fisher but theres no way I'll buy from a company with such screwed up support.



Edited 2 time(s). Last edit at 08/10/2010 12:23AM by Joe.

Someone from Minelab called the fallowing day to talk with me about the Excalibur. Although they don't have a specific air test guide line, the person I spoke with was very informative and he gave me a somewhat reasonable explanation of why they don't quote air test results. Basically he stated there are to many variables for an air test to make valid assessment of a detectors capabilities. One point however, when he discussed the differences between the Excalibur and CZ-21 he stated the CZ was a single frequency, when I pointed out it was actually a dual-frequency he said oh ya, it was the CZ-20 that was a single and that he had one some time ago. Correct me if I'm wrong, but wasn't the CZ-20 always a multi-frequency detector? I'm not trying to be critical but it just struck me as odd. He did, however, compliment the 21's on their ground balancing ability.
Bottom line for me is that possibly in the future I may look at an Excalibur as a second water detector but it'll after a long wait and see period before I'll feel I can trust Minelabs commitment to their customers and an improvement in turnaround time for repairs. This is based on quite a few recent posts from Minelab users.

The CZ-20 & CZ-21 are both 5 & 15Khz frequencies. I would say...........hunt the beach in all-metal/auto-tune......and enjoy (and learn) the detector before sending it in. I would also be very explicit about the unit being capable of 13"+ on a dime in auto-tune........and have them positively verify this........and to promise it will be returned to you in 'said performance'.