Elton this post is from Nasa Tom (Tom Dankowski ) and all his testing, should get you started (and yes people in the know do know about DST):
I MUST start somewhere...... in regards to the new F75 LTD2. This report is going to be incremental..... as I collect aggregate data. This has been long-term....... and more difficult than meets the eye.
First......... let me paint a bit of the 'difficulty' picture. With the initial onset, batch inconsistencies invalidated data. Incongruencies/Inconsistencies that would produce varying results each day. Now, the largest contributor for my prolonged delay is..... silent EMI. Sparing you the volumes of invalidating data.............. finally; some solidified data has emerged. Multiple F75 LTD2's....... have produced parallel end-resultant data.
Let's start with this: ONLY the ID mode, 9.0, 11" elliptical DD coil, Sens 99, Disc '0'. Remember....... the data provided below is from a batch of PRODUCTION RUN units. I can (nearly) say..... disregard previous LTD2 (especially proto units) data.
Nutshell........... utilizing only a clad dime in Florida low-mineral (primarily silica/quartz) dirt:
bp = 11.7"
cl = 11.8" (Exceptionally 'delayed' audio response)
je = 11.2"
pf = 11.2"
de = 11.1"
bc = 10.1"
FA = 9.8"
And this nominal median averaging............ over a period of months...... worth of aggregate/collected data......... during multiple atmospheric/EMI conditions........... and................. with different F1 - F7 freq selections. It has been a long road of dissection ....... for reasonably solidified data. Selecting different tone options is primarily a 'user preference'...... and hardly affects depth/performance. When invoking the 'boost process' modes..... many times...... it can audibly be heard that the LTD2 is imminent of ....... and right at the threshold of inducing EMI.
Remember...... it is still a F75....... and nearly all other (old) provided data..... still stands.
I will provide 9.1 data...... as aggregate data solidifies.
I will also provide all-metal performance in time.
Then........ 5" DD coil data.
Now....... with hundreds of hours of use...... I can safely report nearly a 85% reduction in EMI in 9.0. Switching to 9.1 does add a bit more EMI mitigation.
It is more difficult to see any form of pronounced depth/performance/gain whilst Disc is 4, 3, 2, 1 or 0......... and the subsequent Disc of 20 and above. It still exists; yet, is more subdued.
What I am still having difficulty ascertaining concrete data is..... measuring performance gain/loss between 1N audio.............. and FA process. (Yes, you can invoke both). 1N does give a substantial order-of-magnitude "fatigue reduction" in carpets of nails relic hunting capacity. FA process is extremely fast, and has marked performance gain providing enhanced adjacent target separation characteristics. This is to include hunting in carpets of aluminum trash and/or hunting carpets of nails. This process is extremely fast; yet, does not 'unmask' in it's true semantic definition.
FA certainly takes getting use to. For instance....... a clad dime at the 9.0" to 9.8" depth in clean dirt...... is merely a slightly elongated audio 'tick' (click); yet, to the astute/tuned ear...... still discernible/intelligible.
So far........... in a nutshell............ it's an enjoyable detector to use. ((( I hardly realized how much steroid/overdrive/EMI/high order-of-magnitude "fatigue factor" tolerance I had developed whilst hunting with the older generation F75 LTD...... and still do. )))
More data to be documented.
Now let's talk 9.1. All of the below data will be exclusively 9.1 ...... and you can compare it to the (above..... exclusively) 9.0 data.
ONLY the ID mode, 9.1, 11" elliptical DD coil, Sens 99, Disc '0'.
Utilizing only a clad dime in Florida low-mineral (primarily silica/quartz) dirt:
bp = 11.4"
cl = 11.6" (Exceptionally 'delayed' audio response)
je = 10.6"
pf = 10.6"
de = 10.4"
bc = 9.8"
FA = 9.7"
These numbers are not quite (but almost) 'linear' to the 9.0 numbers. . . . . just a bit less (overall) depth.
In bp process mode..... there is a bit of a lag/delay in audio response to the detected target. If you have a standard F75 SE/LTD....... this audio lag delay would be akin to ...... somewhere between the 'bp' and 'cl' modes. It does take a bit of learning-curve time to get accustomed to. This 9.1 rev....... is 100% DST....... and appears to provide approximately 7% more EMI mitigation.
bp & cl modes present a 'time lag' delay in audio response to a detected target. [[[ bp & cl audio lag's ]]]
FA mode is the exact opposite (both 9.0 & 9.1). The audio report is quite premature. In fact...... BEFORE the target is under the coil.... the detector reports the audio response. [[[ FA audio response leads ]]]
On ANY F75 (old or new).......... the more you lower the Disc....... the stronger the propensity for the detector to ID non-Fe targets more accurately. This is also true with the T2/F70 & Makro Racer.
If you can keep the coil close to the ground.......... will easily ascertain the depths listed above (in Florida low mineral dirt). If you need to have a 5" or 6" air-gap above the ground....... THEN there is a greater loss in depth/performance....... as compared to the noisy F75 SE/LTD's.
So far.......... I have yet to find need/purpose/function for 9.1. The forfeit of a bit of overall depth/performance coupled with a mild increase in audio lag...... is somewhat disconcerting. On the contrary........ 9.0 is very applicable/usable/value-added.
Zero difference/change in battery consumption on LTD vs LTD2.
All-Metal Mode. This is a scientifically difficult mode to report...... as threshold/ears/re-tune can dictate final resultant; yet, some good data can be extrapolated. First, , , , for all testing, I used 11" DD coil, 9.0, Sens 99, Ground Balance of '90' and 'Motion' mode. Buried clad dime in Florida dirt. I was always seeking to hear a slight, but audibly intelligible threshold change.....enough to be categorized as a positive target response. Also, the process modes that you can select whilst in ID mode...... carry over to the all-metal mode. (With several unique observations I will discuss later).
bp = 11.6"
cl = 11.6" (Elongated audio response)
je = 11.0"
pf = 11.1"
de = 11.0"
bc = 10.1"
FA = 10.4"
Notice how there is not as much linearity carried over from the ID mode results. And notice the All Metal depth was slightly less than ID mode. Largest contributor for this phenomenon/resultant is due to Florida's low mineral dirt. As a qualifier...... I must say this: Some of the process modes required changing the 'Threshold' a small amount..... so as to maximize detectors audible intelligence.
* Ironically.......... performing only air-tests........... and depth/performance is nearly always at maximum performance/depth....... even when switching through (and testing) all of the different process modes. The only change/difference is...... the 'length' of the audio response. Invoking 'cl' mode ... (then switching back to All Metal mode).......... and the targets audio response is elongated.
* Testing the 'Static' mode is too interpretive ...... with largely varying resultants. When you reset the SAT/threshold audio...... by pulling the trigger (and releasing)..... THIS ALONE can have a dramatic effect on depth/performance; hence, too many variables preventing solid/repeatable data.
Okay. 9.1 performance/results:
bp = 11.5"
cl = 11.6" (Elongated audio response)
je = 10.9"
pf = 11.0"
de = 11.0"
bc = 10.0"
FA = 10.3"
There is minimal differential/delta in performance/depth whilst comparing 9.0 to 9.1........... All Metal -to- All Metal.
* There is a slight EMI mitigation enhancement whilst in 9.1....... and All Metal.
* Whilst in All Metal......there is a large performance difference ........ in regards to depth........ whilst comparing air-tests with "in real dirt" results. Especially with low conductors..... like a nickel. I can acquire a nickel at 19"++ in an air-test. In the ground....... at best..... is 12.8". Interestingly........... if the nickel is 12.6" deep.......... you can sweep the coil 4.0" above the ground (nickel is a total of 16.6" distance from the coil) and still clearly detect the nickel. This is to say..... the All Metal mode is more air-gap forgiving (when compared to ID mode).
* Another ironic observation is............ when FA mode is invoked........... I can acquire a dime at ... just over 10" ... in real dirt....... IN A TEST GARDEN ENVIRONMENT ONLY! In the real world....... on live hunts........ it is rare to acquire a clad dime beyond 7" depths. This seems to only hold true for the FA mode. This is the same phenomenon the XP GMP encounters. I can acquire a 12.0" clad dime in a test-garden environment ONLY. In the real world........ the nominal/median average of the GMP (with stock 9" DD coil)..... is in the 7" depth range,,, on a clad dime.
* In air-tests............... switching through any/all of the process modes (then invoking All Metal mode)........ and there is a very minimal gain/loss. Nearly the same air-test distance performance. In the ground...... the resultant differential is dramatic.
* Even with NO audible EMI............ switching through the F1 - F7 noise-cancelling/EMI mitigation Freq's...... there is certainly notable performance changes. One "silent EMI" freq..... as compared to another "silent EMI" freq. THIS is where a large amount of my reporting/documenting 'delay' emanated/stemmed from. WHAT do you choose. HOW do you 'average'. Then.............. will tomorrow's atmospheric EMI level/status change the results........... from day-to-day? Yes! Some days.......... the delta/differential/change........... is minimal. Other days...... and it's fairly dramatic. (The woe's of utilizing a ElectroMagnetic detection device......... in a ElectroMagnetic atmosphere....... on a magnetic/ElectroMagnetic Core Earth!!! )))
Because audible EMI is quite minimal on this new LTD2 platform...... I have had minimum interests in testing/data collection for Sensitivities of anything less than '99'...... as long as EMI is silent.
My test-garden dirt is 1-bar dirt. (0.1).
