Xterra 705 18Khz Coil Null

[bradwheat1972]

Hello all,

I was just messing around with my 705 and put the 5x10 18Khz coil on. I passed some of my silver bullion dollars and Morgan dollars over it and it nulls out in all patterns in the discriminate mode. The funny thing is when I pass my 1921 half dollar or other smaller denominations over the coil the detector responds. So I switched to my 10.5 dd and the bullion and Morgan dollars now respond. So one more test, I fired up another one of my detectors and all the coins responded. If it were a coil problem all the coins should have responded with the same null right? Has anyone else experienced this? Thanks in advance and keep on diggin'em up!

Brad

 

[ronhob]

It may null out if you have 48 discriminated because of the wrap around effect Randy speaks about in his E-BOOK. The high TID numbers really get scrunched together with the HF coil.

 

[crusher28]

I also find tis to be true with some Xtera coils. But what I do before I go hunting with any of my Minelab detectors is to test them in all patterens (disc mode). MY Xtera 705 will null out all gold rings and nickles in pat. 2, or pass right over them with out any sound at all.
But after many years (40) of hunting. I will hunt in ALL METAL and listen for different tones. I use Fisher and Minelab detectors only. You get use to the tones each one makes and the TID numbers are 80% right on the mark

 

[glenmaki]

Exactly the reason I have been using all metal, no discrimination, don't want to miss anything. Takes some time to get used to but it works well.
Glen

 

[michaelosully]

Guess I just don't understand why anyone would choose to hunt in anything other than All Metal, no discrimination, with threshold set at barely audible??? At least 99% of the time when out 'random hunting'. Seems to me that you will identify all potential targets (that your machine and coil is capable of finding) with these setting, won't you? I don't really need the machine to tell me when to dig do I? I can tell by tone or by TID what the machine has found (within the same degree of accuracy the machine would utilize for discrimination patterns) and I can use my gray matter to decide to dig or not. Am I missing something here?

OK, I understand there are many circumstances to utilized the discrimination feature and the patterns programming feature offered on the X-terras. But, you can always hunt in the AM mode and then 'toggle' to a pattern/discriminate if you need the machine to tell you 'dig this target' and then go back AM.

I hunt many campsites littered with foil & pulltabs but I still hunt in AM with no discrimination...I just choose to not dig the foil & pulltab tone and TDI rather than 'disc it out'. These tones & TID (which I could 'disc out') often tell me where the oldest firepit or fire ring used to be located and where I am most likely to find coins or other relics that were lost in the past.

Anyway, what I am generally asking is: Why would anyone risk the '"wrap around effect" occurring or risk passing over anything they might want to dig by relying on the machine to disc out a particular segment on your TID display when you don't have to take that risk? Randy says in his ebook that he hunts in a discrimination pattern set to not discriminate out any notch segments most of the time. I think this is the same as hunting in AM but does not require 'toggling' to AM when the machine is turned on...IS THIS CORRECT?

I like to think I am maximizing my 'potential targets' and learning the most about the 'hunting ground' when I hunt in AM or in a pattern with no discrimination.

 

[TURNMASTER]

I THINK part of the issue is that the HF coils have a smaller Bin Width at the high end of the scale. I also believe that HF coils ID slightly higher than my MF coil. register, or null out. I prefer not to hunt with 48 notched out. I do sometimes though because it stops the Iron Wrap a lot. If I am hunting and get tired of the Iron Grunt I go to a pattern with the negative notches notched out. I also use AM more and more. I get a lot more stability at the upper end when using the MF DD coil.

I have tested with Morgans and I hit them hard with all coils. I have never tested one with 48 notched out though. I will try that and post results.

Jeff

 

[Digger]

Randy says in his ebook that he hunts in a discrimination pattern set to not discriminate out any notch segments most of the time. I think this is the same as hunting in AM but does not require 'toggling' to AM when the machine is turned on...IS THIS CORRECT?

The other difference between zero discrimination and All Metal is that All Metal detects anything metal. Zero Discrimination detects the metal and uses the parameters established by the notch segments to categorize each target within one of those notch segments. Keep in mind that the notch segments were established with specific ferrous and non-ferrous properties in mind. On deeply buried iron, that is most generally the -8 notch segment. In All Metal, those same deeply buried pieces of iron will be recognized as metal, and generally bounce between -8 and +48, giving that occassional burst of high tone, blended in with the low tones. It may still bounce a bit between the lowest ferrous and the highest non-ferrous notch when using zero discrimination. But generally, zero discrimination offers a more consistent -8 TID on bits of iron than it does in the All Metal mode, without having to reject notch segment 48 to minimize the wrap around. JMHO HH Randy

 

[glenmaki]

Randy says in his ebook that he hunts in a discrimination pattern set to not discriminate out any notch segments most of the time. I think this is the same as hunting in AM but does not require 'toggling' to AM when the machine is turned on...IS THIS CORRECT?

The other difference between zero discrimination and All Metal is that All Metal detects anything metal. Zero Discrimination detects the metal and uses the parameters established by the notch segments to categorize each target within one of those notch segments. Keep in mind that the notch segments were established with specific ferrous and non-ferrous properties in mind. On deeply buried iron, that is most generally the -8 notch segment. In All Metal, those same deeply buried pieces of iron will be recognized as metal, and generally bounce between -8 and +48, giving that occassional burst of high tone, blended in with the low tones. It may still bounce a bit between the lowest ferrous and the highest non-ferrous notch when using zero discrimination. But generally, zero discrimination offers a more consistent -8 TID on bits of iron than it does in the All Metal mode, without having to reject notch segment 48 to minimize the wrap around. JMHO HH Randy

Thanks Randy, kind of missed that info before. I will try that method next time out.
Glen

 

[michaelosully]

I also had not understood the difference between the AM mode and the pattern with no discrimination mode. I will now set my pattern 1 to zero discriminate and give it a go.

Thanks bradwheat1972 for posting this thread and thank you Randy for the detailed explanation of how zero discrimination works!