jd88047 said:
metalpopper said:
jd88047 said:
To better understand my coils I would like to know if the frequency is set. I see a lot of coils set at different freq for other detectors. Is this the same for Etrac coils? I have four coils I would like to know the freq of. The coiltec 6 inch, the fbs800 8 inch, the stock 11 inch coil, and the sef 8x6 coils. Thanks in advance.
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"Hello there JD"
You
don't need to be concerned about a specific coil frequency of
any genuine coil made for the MINELAB E-trac.
(They will indeed have an 'optimum' frequency, but of relatively low 'Q')
[size=x-large]WHY?[/size]
The FBS system is BROADBAND...(1.5 KHz up to !00 KHz in theory (28 Odd Harmonics of 1,500 Hz)
and any Etrac coil is 'designed' to accommodate ALL of those harmonic frequencies. ....matt
The E-trac uses PULSE TRANSMISSIONS and TIME DOMAIN receiver methodology.
I'm used to tailoring my specific coil to my hunt. I have two other single freq detectors that run at different frequencies. Guess I have some more reading to do. Being new it doesn't matter at this point. But I will be tweaking the etrac for each hunt. I really am having fun with TTF. Love open screen. I have some very challenging sites here. So far I havent had to pull out my F75.
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Hello again JD....thanks for your thoughts on the subject.
You are right about single frequency detectors.....for they can 'out-perform' multi-harmonics in the right situation..(Whatever that may be)
'Whatever that may be' means that you know WHAT SPECIFIC CLASS OF TARGET you're hoping to find.
Which is different from searching for whatever lady-luck may cross your path with; and in which case Multi frequencies come into their own.
WHY ?
Well, every unique target has an 'optimum response' to a particularly 'group-of- frequencies'. If your detector accommodates that group, then you stand the best chance of finding that related target.....
you may find it even if your unit doesn't 'match'....
.but you may not find it as deeply as a matching frequency detector does.......
If your desired target is in heavily ferro mineralised soil...and at depth....then the other k factor comes into play regarding 'best frequency'.
What's the k factor?
Well... complicated,,,but simply stated...."You must 'get-through' the grit first....to reach your target.....mmmmm?
So which frequency should you use?.......The LOWEST frequency that relates to the 'group-of frequencies'.
Let's imagine you're hunting silver dollars....>90% silver............let its Optimum group of frequencies, = 1000 Hz to 4000 Hz
In 'good' lo Fe soil.....use 4,000 Hz......in more difficult Fe soil... use 1,000 Hz..........
That's a hypothetical but descriptive way of trying to explain the concept of frequencies and target relationships.
So the soil 'ATTENUATES' the searching-flux's power; IN AN EXPONENTIALLY DECREASING manner, related to the FREQUENCY, as it penetrates and 'reacts' to the soil's resistive and 'inductive-components', on its way to the target.
THIS IS WHY MULTI-HARMONIC-PULSE transmission methods are best for general searching for a broad range of targets AND GROUND CONDITIONS......Your Etrac...Your CTX 3030....Your WHITES V3 in 'Best-Data' mode.....But if you know the frequency relationship of any particular targets you prefer to find..then your WHITE's V3i...Also gives you 3 individual frequencies modes....and better DEPTH.
Hope that brief overview helps to provide some insight to the why- and wherefore of detectors and choice of frequencies.....matt