A lil' Fisher/Tek Spec comparison

[BarnacleBill]

[attachment 118737 FishSpecTable.gif]
A few observations:

1. The T2 has the lowest Lag(highest speed).

2. The F70 & F75 are the most sensitive with the spec being the same.

3. The overload figure from the manual for the F75 appears to be written for the 10" Concentric, NOT the 11" bi-axial with which it was released.

4. The F5 & Omega on paper look much less sensitive, though the lower frequency may present some advantage in more mineralized ground, and for higher conductors.

5. Though less sensitive the F5 & Omega appear more prone to overload, and I believe that there has been some discussion of overloads with the F5.

HH
BarnacleBill

 

[Mike Hillis]

Glad you put that together BB.

Wow...that 11" coil trippled the reactive and resistive overloads

That expains the merits of a DD coil.

HH

Mike

 

[Bill Ladd]

Always thought it was due to running the 21 disc in the 40 points iron range, but I guess that lag speed must really help too....
Anyone know the lags for say the Edge or C$? Or maybe Los Banos kept that proprietary.....Could be even faster??
Thanks for the post,
Bill

 

[BuckeyeBrad]

again, interesting data and thanks for compiling it. I tried to see if your "on paper" results, particularly on lag, are consistant with how these (or a similar cross-section) detectors see actual good targets colocated with iron. I tested the Gamma with stock coil, the F-75 with the large elliptical concentric, and the XT-70 with it's stock 7.5 9" coil. I used an 1865 indian cent with a small well rusted tack buckle that's about 1.5" square. I spaced the two targets about 2" apart. The supposed equal lag of the XT 70 certainly didn't show up as equal in my test. With it, I never got the first non-ferrous ID or tone. Also the Gamma was considerably faster than the XT and right there with the 75. Actually the "relatively slow" Gamma gave the best two way signal on the average of them all.

 

[BuckeyeBrad]

I misinterpreted and mistakenly confused your data of the F-70 thinking you were using the XT 70 like you had in your GB post. Too many 70's out there. Sorry about that.

 

[Cal_Cobra]

A few observations:

1. The T2 has the lowest Lag(highest speed).

4. The F5 & Omega on paper look much less sensitive, though the lower frequency may present some advantage in more mineralized ground, and for higher conductors.

5. Though less sensitive the F5 & Omega appear more prone to overload, and I believe that there has been some discussion of overloads with the F5.

HH
BarnacleBill

Interesting notes Bill.

Being that the speed differences are in milliseconds, unless measured by a computer, nobody can discern a difference speed between machines IMHO.

I've found that the F5 is very sensitive to gold, including small nuggets, whereas with the same stock coil (the F5 and F70 seem to share identical stock coils, at least in size) the F70 is less sensitive to gold. This seems counterintuitive, as I've always read that higher frequency machines were more sensitive to small gold.

I've discussed the F5 overload issue here before. I've found that the F70 will also overload on small shallow/surface targets, BUT the way it handles it is much different. My F5 will blank out until it hits a non-overload target (raising the coil doesn't help after the overload occurs, whereas it may help if it's raised before hitting the overload target), where the F70 simply gives it's overload signal, but keeps working away without blanking out.

Thanks,
Brian

 

[marcomo]

Interesting points, Brian.

I have the overload situation with the F5 as well, but mine seems a little bit different.

Sometimes my machine will blank out until it hits another target, other times I can raise the coil and get it to give me a reading.

My feeling is that it depends on how "overloaded" the circuitry is.

Bigger targets on or very near the surface will blank it out until the next target, no matter how much I raise the coil.

With smaller targets on or near the surface I can get a reading and get rid of the overload signal by lifting the coil and sweeping again.

I have yet to find a coin sized object when the detector stays blanked out after lifting.

 

[Mike Hillis]

Bill,

I bet the CoinStrike has at least the same or better reactive/resitive overload numbers as the T2/F75. The CoinStrike has been the only single freq machine that can get any real depth in some of my ground conditions using a concentric coil. Real depth with target id, not a chirp that can't be told apart from ground noise.

HH

Mike

 

[LilloEsquilo]

I think the T2 is really under-rated. All I know is it got me coins in iron that I didn't get using other machines and it impressed me with the tests I threw at it (like finding a coin near or under a nail). And it's no slouch on depth either. For the money it's a lot of bang for the buck. Hard to beat the ergonomics of it too. And battery life doesn't get much if any better. I'm a fan of it too Bill.