Reealy Techinical Question on F75 LTD

[grumpy]

Ok I have a really tech question for the ones of you that actually understand what is under the hood of a 75 ltd.
I do not have a lot of tech experience on electronics or any thing related except for high freq welding; tig;
Here is my ? to you that might have a background and tech info on the machine;
When you have a high freq welder the sine and wave thing goes plus neg up and down; do these metal detectors have a simular event in them? Why is i have noticed that at times quite often actually i get a number on a pass of like a 30 a 50 and a 80 ( not actual numbers) two of the numbers in the swing will add up to the third or such combo: These numbers bounce arund but usually the accurate number will repeat the best but not always. today thirty 40 and 70 came up and it best to the seventy which should been a dime or early penny but it was a nickel:
Just wondering if anyone thought or had reason to believe it is a anomoloy howeveryou spell that; in the elec that causes the numbers to multiply divide or such mathmatically like a sine wave?
Just a question that thought might explain some of the number bouncing;
dig em all and dont worry about the missed goodies
Grumpy

 

[TerraDigger]

Perhaps Dave Johnson can give an explanation.

 

[Dave J.]

If two consecutive numbers add up to a third, it's just coincidence.

--Dave J.

 

[NE Digger]

Most "bouncing" numbers can be attributed to a few things. co-located targets.. failure to find the center of the target.............and improper sweep speed.
If I want as accurate an ID as possible............I do this. Actually...............I do this on every target.
First, pinpoint and find the exact center of the target. Pinpointing will let you know exactly where the target is....and also let you get the "feel" for its size. (footprint). lots of big iron will often ID like coins.....but the huge footprint and extra bars on the FE304 meter most often give it away. Iron also just sounds harsher. coinage tends to be softer and sweeter. Ok..once you have found the exact center of the target.......swing directly over it...............but faster than you would normally swing when hunting. Now...............most times the audio will suffer a bit when you do this......but the VDI will settle right down...and give you a much more accurate ID. In a nut shell......I use a slower sweep speed for general hunting..................but pick it up a bit when IDing. The F75 recovers so dang fast.....it will literally show everything that passes under the coil pretty much instantly. If your sweeps are sloppy..its seeing something different every time you swing. THATS the main reason for lots of bouncing.