Changing frequencies. What exactly is it doing?

[RelicDigger1]

Just got back from what started out as a lackluster day of relic hunting, a flat button and some scrap brass. At the end of the day, on a whim, I swapped frequencies and BAM, BAM, BAM...targets everywhere, and in a TINY spot no bigger than a car hood a lot of detectors have been tried (It's a bullet hole).

What are we doing when we increase/decrease the "frequency"? Are we actually going from 13kHz to 13.2, say?

It was simply phenomenal to watch. Changing the frequency seemed to light the ground up despite a heavy nail concentration.

Thanks

 

[Mike Bearden]

and often it can be interference that you may not hear thru your headphones.
Funny thing is that even when you don't actually hear anything wrong it could be that changing the frequency just a bump or two either way WILL make the difference and the targets start showing up.
Very much like finding goodies with one machine that has a FIXED frequency until all the targets seem to vanish and then going over the same area again with a different machine/frequency and more targets are found.
We often read post where people are trying out a NEW detector in beaten to death sites and they find good targets that their previous machines didn't see, whether it's depth related, separation quality, or whatever .... I tend to believe a lot has to do with the overall frequency differences pertaing to what KIND of targets are being found.
Low frequency machines do well on high conductive items ( like silver & copper) where higher frequency machines hit harder on low conductive items ( like gold & nickel ) for the most part.
Supposedly .... the all around best frequency for finding the goods with a metal detector is around 12 kHz give or take a little.
With the F-75 running at 13 kHz and the ability to shift it a little .... that puts it right where we want it, still good on gold thru nickel

Hope this helps
Good Hunting
Mike

 

[RelicDigger1]

It does help Mike. I've seen Nautilus go through, then Tejons, and MXTs. Even F75s. This is a place that sees heavy hitting as relic hunters move on to other sites. They'll hit this spot then move on. I've done the same, but we always hit it because it's been so good in the past. I hit it yesterday before quitting time just to dig "one more relic." But when I swapped to F5 (out of an attitude of "it can't be any worse," mind), I didn't take one step before I got a WOMP, WOMP, WOMP in one swing. I thought that strange because I knew I had dug several bullets out of this exact spot. My filled-in hole still visible, and I was partially digging in the same "old" hole. But no more signals were forthcoming after those first bullets with any other detector. After digging an eagle button yesterday and a three ringer, I swept around the area and dug even more targets, also in areas that've been hammered. I agree in that when you're trying a "new" detector in an area using a different frequency, you'll more than likely dig stuff simply due to that frequency shift rather than the new detector being the one to beat. But my conclusion with this (albeit after just a few mins of swinging) is that I have seven detectors to take over this area now with the F75. F5, whatever frequency it is, is the frequency that I'll be using next trip in! Thanks for your insight Mike

 

[Mike Hillis]

F1 = 12,821 Hz

F2 = 12,876

F3 = 12,931

F4 = 12,987 DEFAULT

F5 = 13,043

F6 = 13,100

F7 = 13,158

HH

Mike

 

[RelicDigger1]

Awesome! Thanks Mike. That gives me an idea as to where the 75 is operating as compared to the other detectors I've had in there.

 

[Mike Bearden]

Thanks Mike, I kind of thought we me hear the specifics from you on this

 

[Brainwasher]

I guess now I have a new question. If changing frequencies can illuminate new targets, does a multi-frequency detector have an advantage over a single frequency detector in that it is maybe running 28 frequencies simultaneously? Is it more likely running say from 1 to 100 Hz to find more stuff over a single frequency detector running at only 13 Hz. Will it go deeper and be more sensitive at the same time than the single frequency that is not reaching both ends of the frequency spectrum?

 

[Mike Bearden]

This was posted in 2004 and it makes for some good reading, have a look and HAVE FUN

http://www.findmall.com/read.php?19,67264,page=1

 

[gary (central va)]

n/t

 

[RelicDigger1]

F5. It made a world of difference just swapping it from F3 to F5.

 

[Brainwasher]

Thanks Mike, that helped...I think. Makes my head hurt actually, but I think I got it now.

 

[UK Brian]

I think the thread went a bit off track by bringing in Minelabs multifrequency machines . Without returning to the whole arguement of how many frequencies they use (not transmit) and the whole harmonics question the F75 and T2 'extra' performance wasn't gained by the extra depth or sensitivity to a specific metal. Such a slight shift makes no difference apart from reducing the very real interference problems that, as Mike points out, may be inaudible.
From the above posts it seems people make a trial and error guess at a different frequency to use. This works to a degree but again is there a degree of interference your still not hearing.
If the machine is put into a high gain mode/maximum sensitivity, zero discrimination and even the coil held up whilst you revolve to try and locate any source of interference, anything to increase the problem to maximum, then you can swap through the frequency changes to select the very best one. Then set the machine to the required settings for the specific site and whats being searched for.

 

[digitrich]

n/t

 

[Mike Bearden]

n/t