using the off set on the 705

[bubber]

Using the XT 705, in highly minerilized ground,loaded with hot rocks assuming the ground reading was 15 would the offset be set at 10 or 20, using an offset of 5? and would this setting help with hot rocks? I just can't seem to understand about the offset. Thanks

 

[BarnacleBill]

At 15 a +5 setting = 20 or a (-)5 setting = 10.

Remember it only works in GB Tracking.

Example: The ground is Tracking around 15, if you manually GB to a Hot/Cold Rock & it GB's at 25 then set the Tracking offset to +5 which = 20, that being half way way between 15(the ground) & 25(the rock).


http://www.findmall.com/read.php?55,941152,941152#msg-941152

 

[Digger]

After I made my post, I see where BB beat me to the punch again. I was simply going to delete mine, as he had a great answer. But after having spent 15 minutes typing a response, I'm going to leave it up!

I agree, the terminology is confusing. In manual ground balance without tracking or tracking GB offset, pressing the + pad will actually make your ground balance more negative. Pressing the - pad will actually make your ground balance more positive. If the "proper" ground phase reading was 15, an offset of 5 could make it either 10 or 20, depending on whether you want a positive offset or a negative offset. If I pressed the + pad five times while setting my offset, it would result in a negative ground balance offset of 5. And, if I checked it at the precise place where the "normal" ground balance had been the 15, my display will now read 20. In other words, the tracking GB number displayed will include the offset you programmed. Going the other way, if I wanted to program in a positive ground balance offset, I would press the - pad 5 times, resulting in an constantly updated tracked ground phase of 5 points more positive than the detector would have been without using the offset. If I pressed the GB pad and the number showed a 19, I would know that the "normal" GB at this precise spot would have been a 24, if I had not programmed in a positive ground balance offset of 5. Again, running a positive GB means using the - pad to lower the number. Running a negative GB means using the + pad to raise the number.

I would suggest you try a positive GB offset if your soil is heavily mineralized with magnetic mineralization. Can't tell you how much as all areas vary. But having a positive GB offset could help identify those hot rocks. Another suggestion would be to use the small DD coil. The smaller the footprint, the less adverse effect those hot rocks will have at any given time.
HH

Randy

 

[bubber]

Thanks for the replies, I'll be prospecting in No. CA later on, and the hot rocks are terrible. I do use the 6 in HF coil. I was using an XT 70, and the hot rocks just drove me nuts. so I thought I'd try the 705. see if it makes any difference.

 

[David]

I have an X-70 and do not fully understand the 705's off-set GB. But I know on the old manual GB dial analog units(and some new ones like the Vaquero, Gold Bug-2, and Scorpion) a person sets the GB 'slightly positive', meaning the sound increases when the coil is on the downward pump towards the ground.

The best coil is the 5x10" HF DD in Hot Rocks and high mineralization. It IS better(ground handling, quieter) than the round 6" HF DD. You could also use the round 10.5" HF DD if you have one, but the disadvantage of this coil is it will not pick up sub-gram nuggets as deep as the other coils I mentioned above, but will pick up larger sized nuggets deeper.

When I prospect with my X-70, and come across a signal. I switch over to Coin & T Mode(All-Metal), where Hot Rocks come up as -8 and +48, then I ignore them. But if there are 100's of them then this is too time consuming. Also experiment with Iron Mask(IM) up to 20. I wish the TID numbers came up in Prospecting Mode.

Or just hunt in Coin & T Mode(disc. mode) full time for gold nuggets in Pattern 1 which 'knocks out' all ferrous(-negative) numbers and +48. You will lose--sacrifice some depth and sensitivity but it will 'cancel--knock out' Hot Rocks and small 'iron' trash making gold hunting much more pleasant and enjoyable. You could also 'knock out' +2 and +4 for any 'foil' trash as well, if need be.

 

[bubber]

David, about how far away can you pick up ,say a 8.7 gr nugget and about a 19.9 gr. nugget, using which coil. I can only pick them up about an inch away with my XT70, using the 6 in HF coil.or the 5x10 HF coils. haven't had a chance to try the 705

 

[David]

David, about how far away can you pick up ,say a 8.7 gr nugget and about a 19.9 gr. nugget, using which coil. I can only pick them up about an inch away with my XT70, using the 6 in HF coil.or the 5x10 HF coils. haven't had a chance to try the 705

With my X-70 and the 5x10" HF DD coil, I used a 1973 US Nickle(5c) on the flat, that comes up a +12 in Coin & T Mode(All-Metal) which is about the same conductivity as gold nuggets. In an air-test indoors(raining outside) with the sensitivity set at 25, I can pick it up with a loud signal at about 7" inches(used a Plastic 12"-foot ruler for measurements) away from the bottom of the coil.

In Prospecting Mode(All-Metal) with sensitivity set at 25, I can easily pick up the Nickle at about 10" inches away from the bottom of the coil.

So if you are getting only about an (1") inch away, there is something wrong somewhere ??

 

[bubber]

Maybe so, but that nickel has a lot more area to detect than my little nugget, but I appreciate the info.

 

[David]

"8.7 gr nugget and about a 19.9 gr. nugget"

OK, do you mean grains or grams? (I thought you meant grams, as 19.9 gram nugget is pretty big, about the same size a a nickle. If you meant grains then you are right that is small.)

 

[bubber]

Yes, I meant grains, Sorry, I should have been more specific

 

[bubber]

Digger, Barnacle Bill One question I forgot to ask, when using the offset, does the 705 then ignore hot rocks, or does it still beep on them? If it still beeps on them, what is the point? Thanks for your patience. I appreciate it no end.

 

[TURNMASTER]

Timely Topic,
I was wondering about this very subject.

So, If I have an old site that GBs in the 10 to 20 range depending on precice location, we will say 15.

Then when I GB manually at 15 indicated on the control, I should get better results if I offset positive manually by say 5 points to 10.

If what I have been reading over the last year rings true, then I should be able to coax out a little more depth and stability with a more accurate ID.

Did I get this right? --- Understanding that conditions vary.

Jeff

 

[Jackpine Savage]

It may or may not beep on them because the mineral content can vary from rock to rock. With tracking on repeated sweeps over a hot rock will lessen or even eliminate the response, adding in an offset in this case many just make things more difficult and of course then you are off the proper GB setting for the surrounding soil. Since each and every rock will vary in mineral content the best you can do in an area with a lot of them is set a manual GB that lessens the response to the majority ...forget tracking and offset.

Tracking offset used properly in disc mode can be an aid in certain situations. It take lots of experimentation to see if your conditions actually merit its use.

Tom