Goldbug 2 -6.5" vs 10" coil?

[garyflal]

I'm trying to figure out if I really need the 10" coil. I know it will cover 50%+ per sweep but from the air tests on one of the dealer's web site the 6.5 is deeper on nuggets up to 1 dwt. I'll be hunting mostly around NE GA or NC where most if any nuggets would probably in the fractional grain to grain size. Any thoughts of experience would help. HH Gary

 

[Ralph Bryant]

Gary,

The GB-II is probably the most sensitive gold machine on the market for smaller gold (under one gram nuggets and flakes). Especially so in your part of the country, the vast majority of gold is going to fall into this smaller sie range.

With any detector, the smaller the coil you use, the smaller and more concentrated are the flux lines (detection field) emitted by the detector at the coil. This gives better sensitivity to smaller targets just for that reason. The small coil will always give you better target sensitivity to the smaller gold than the larger coil, even though the larger coil will detect larger nuggets at greater depth. Most users are surprised though, at how little difference there really is effectively between the two coils. There is some slight give and take with either coil, but I have seen some sub-GRAIN flakes of gold on the order of 1/10th of a grain and smaller taken with the GB-II and the smaller coil. It's a super combination. But that being said, I think I would opt for every size of coil available and do some deeper detecting for some of those scarcer large nuggets if in gold country. For me, there is always this nagging doubt in the back of my mind whether I have missed something GOOD that I walked right over because is was just barely out of the range of my smaller coil. If you're in a good gold producing area, why not take full advantage of the capabilities of your detector ? It just might pay off in the long run, and just one single large nugget could pay for all available coils, the detector, and maybe even the vehicle that got you to your hunting site. I've seen it happen before !

Ralph

"Two Pounds of Gold"

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[garyflal]

Ralph thanks for the info. I saw your nuggets on the other forum this morning. Very cool. I wouldn't know what that much gold would feel like. Thanks for sharing that. HH Gary

 

[steve herschbach]

Hi,

<center><b><font size="2">Here is a chart by Fisher comparing Coil Size vs. Depth - Fisher Gold Bug 2</font></b></p><div align="center"><center></font><table width="400" border="1" style="text-align: center; border-collapse: collapse" cellpadding="0" bordercolordark="#808080" bordercolorlight="#808080"></font></font><tr><th width="130"><font face="Verdana, Arial, Helvetica"><font size="2">Nugget Size</font></font></th><th bgColor="#C0C0C0" width="99"><font face="Verdana, Arial, Helvetica"><font size="2">6.5" Coil </font></font></th><th bgColor="#C0C0C0" width="99"><font face="Verdana, Arial, Helvetica"><font size="2">10" Coil</font></font></th><th bgColor="#C0C0C0" width="99"><font face="Verdana, Arial, Helvetica"><font size="2">14" Coil</font></font></th></tr><tr><th width="130"><font face="Verdana, Arial, Helvetica"><font size="2">.5 grain</font></font></th><th width="99"><font face="Verdana, Arial, Helvetica"><font size="2" color="#FF0000">1.5"</font></font></th><th width="99"><font face="Verdana, Arial, Helvetica"><font size="2">.25"</font></font></th><th width="99"><font face="Verdana, Arial, Helvetica"><font size="2">on coil</font></font></th></tr><tr><th width="130"><font face="Verdana, Arial, Helvetica"><font size="2">.8 grain</font></font></th><th width="99"><font face="Verdana, Arial, Helvetica"><font size="2" color="#FF0000">2"</font></font></th><th width="99"><font face="Verdana, Arial, Helvetica"><font size="2">1"</font></font></th><th width="99"><font face="Verdana, Arial, Helvetica"><font size="2">.5"</font></font></th></tr><tr><th width="130"><font face="Verdana, Arial, Helvetica"><font size="2">5 grains</font></font></th><th width="99"><font face="Verdana, Arial, Helvetica"><font size="2" color="#FF0000">4.5"</font></font></th><th width="99"><font face="Verdana, Arial, Helvetica"><font size="2">4"</font></font></th><th width="99"><font face="Verdana, Arial, Helvetica"><font size="2">3.5"</font></font></th></tr><tr><th width="130"><font face="Verdana, Arial, Helvetica"><font size="2">1 pennyweight</font></font></th><th width="99"><font face="Verdana, Arial, Helvetica"><font size="2">5"</font></font></th><th width="99"><font face="Verdana, Arial, Helvetica"><font size="2">6"</font></font></th><th width="99"><font face="Verdana, Arial, Helvetica"><font size="2" color="#FF0000">6.5"</font></font></th></tr><tr><th width="130"><font face="Verdana, Arial, Helvetica"><font size="2">1 ounce</font></font></th><th width="99"><font face="Verdana, Arial, Helvetica"><font size="2">8"</font></font></th><th width="99"><font face="Verdana, Arial, Helvetica"><font size="2">11"</font></font></th><th width="99"><font face="Verdana, Arial, Helvetica"><font size="2" color="#FF0000">14"</font></font></th></tr></table></center>

As you can see, for 1/4 pennyweight and smaller you are better off with the small coil. Around a half pennyweight you probably still equal the 10" coil for depth with the small coil. At 1 pennyweight the larger coil pulls ahead. But the 14" coil does even better. Main lesson on this chart is you may be better off with a 6.5" coil and a 14" coil if you want to cover the bases.

Steve Herschbach
Alaska Mining & Diving Supply

 

[garyflal]

Steve, thanks for the info. That is the chart I saw previously and got me questioning what coils were really needed. From what I've read, the chance of finding anything larger than a fractional grain nugget here in the SE would be unlikely, but hopefully I'll get out west soon and the larger coils definitely make sense.