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Relation Between CTX 3030 CO number and Weight/Size
Posted by: LawrencetheMDer
Date: February 17, 2018 01:48PM
I've had my CTX 3030 for about a year now and couldn't be happier. With 17" coil and ability to define my area of acceptance, I can cover a lot of beach and not be plagued by to much junk. I can decide whether to dig most coins since their values are fairly stable and I sometimes concentrate on the gold numbers of 12:02, 12:09-12:14, and 12:24-12:36. However, one plague is aluminum foil and another is lead fishing weights.

Both aluminum and lead have the ability to appear just about anywhere along the CO axis; although ALL CTX users would recognize the FE:CO coordinates of 12:15 to 12:23 as push-tab and pull-tab areas. I have had aluminum of various types, usually foil, show-up anywhere from 12:01 to 12:42 along the FE:CO coordinates, with the FE axis more or less stable at 12 with different aluminum and lead objects. Lead fishing weights also span a large range of CO numbers from 12 to 43 as demonstrated in the present blog.

As noted in the CTX 3030 Handbook by Andy Sabisch, the CO (and FE) scale is arbitrarily named and doesn't relate to conductivity as the abbreviation might suggest. As Andy notes on page 15, the CO axis could have easily been named the X-axis and the CTX is not doing some type of metallurgical analysis.

One impression after using the CTX 3030 for a year is that the CO scale from 1 to 50 relates to size and/or weight of an object. For example, it is the smallest pieces of aluminum that ring in at 12:01 and a Can top can ring in at 12:32 or so. To test this impression of CO number and objects weight, I took 11 fishing weights of varying weight (and size), from 12 to 120 grams, and recorded FE:CO coordinates for each with an air test at constant distance from the coil (1").

Table 1 shows the weights and CO numbers, correspondingly. [Ideally the fishing weights should be the same shape, but ya can't have everything.] The FE scale or number was fairly constant at 12, although the smallest weight registered 9, the second smallest registered 14 and the 8th heaviest had an FE of 11. All others had an FE of 12.



The graph shows lead weight in grams (x-axis) against CO number on the CTX 3030 (y-axis). The solid line represents a regression line (log scale) and the R value shows the correlation between CO number and weight. A correlation of 0.894 (with df=9) suggests a very strong relationship between the two measures. In other words, most of the change along the CO axis can be considered a measure of weight, to the first approximation. Lighter objects correspond to low CO numbers and heavier objects correspond to higher CO numbers.



Because size and weight change at the same time (as an object gets heavier it also gets larger), it is not possible to tease apart whether CO number varies more with one or the other. Suffice it to say, however, that an object's weight/size corresponds closely to CTX 3030 CO number. Thus, gold bands can very anywhere along the CO axis. Personally, last year I found a small band (1.22g) at 12:02, after digging 100 foil juice tops, and this year found a larger gold band (10 grams) at 12:14.

If aluminum and lead very along the CO axis based on weight/size, than the forced conclusion is that gold can appear anywhere along the CO axis including in the aluminum range of 12:15-23 and could even occur at cent coordinates of 12:37 and 12:40. Indeed, I'm kept up at night thinking about the report of a hunker of a gold ring appearing at 12:37 - a coordinate reserved for a cent. Perhaps it is best to dig all targets, regardless of CO number...ya just never know.



Re: Relation Between CTX 3030 CO number and Weight/Size
Posted by: IDXMonster
Date: February 17, 2018 02:16PM
Good write up. If you’re beach hunting for gold,I’d assume you’d dig ALOT more different numbers than silver coin hunting in turf. Nice job of paying attention to stuff!

Re: Relation Between CTX 3030 CO number and Weight/Size
Posted by: stephenscool
Date: February 17, 2018 09:42PM
With my testing i can get pd,pt,gold,s925,s999 anywhere along the 12 line. A large 24k ring rang up as far right as it can go.... but on the 12 line. Last summer I had an odd 24k pendant that rang up on my buddies ctx as 12:20. 3g hollow pendant. I will likely dig anything along 10,11,12,13,14... eventually getting rid of 10 and 14

Re: Relation Between CTX 3030 CO number and Weight/Size
Posted by: diamondcutter
Date: February 19, 2018 01:22PM
The CTX has the great ability to dial in on what you want to find, the options allow it seems endless programs to be made and dialed in for your purpose.

Re: Relation Between CTX 3030 CO number and Weight/Size
Posted by: stephenscool
Date: February 19, 2018 05:16PM
Quote
stephenscool
With my testing i can get pd,pt,gold,s925,s999 anywhere along the 12 line. A large 24k ring rang up as far right as it can go.... but on the 12 line. Last summer I had an odd 24k pendant that rang up on my buddies ctx as 12:20. 3g hollow pendant. I will likely dig anything along 10,11,12,13,14... eventually getting rid of 10 and 14
I didn't test 10k, 14k, or silver coins.

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