Hey guys,

I've been reading up on the F75 here and have just registered today.
I think this is THE most informative forum on the F75 I've seen so far.
Hat's off!

Reading all your and (Major)Tom's input has left me with a few burning questions to ask concerning the F75/F75LTD.
Call me obsessive, I don't care ;-)

For instance: I'm wondering what actually happens when you select PF (Plowed Field mode).
How is it different from DE or JE?
I know JE is a high gain mode for low conductors (i.e. small jewelry) and that DE is kind of a jack of all trades, but what makes PF really different?

I've read in the manual that it's designed for uneven terrain, but I would like to understand what happens and how it would outperform DE on a plowed field.
Is the ground balance changed, or is there more to it?

Same goes for BP and CL on the new F75 LTD; what is different?
How does Mr. LTD come by his extra inches :-)
Is it the way the signal is being processed?
Is it higher output or is it a different processor-clockspeed that does the trick?

And what's the idea behind the high gain area's in DE mode below DISC 5 and upwards of 20?
You already have a JE mode if you need extra sensitivity, so I don't get it.
Is it to negate excessive EMI in the 5-20 range or just to get a more balanced allround mode, for 99% of the situations?

There are a whole lot of (very useful) discussions going on on this forum, especially about how things are performing the way they are.
Also comparing F75LTD vs. standard F75 vs. other brands is very useful, but my input would be to question the why's and the how's of certain modes.
And this seems like the best place to ask.

Peter

@Tom: I just finished posting this message, when I saw you have already answered one of my questions in the other posting.
Sorry, about starting 2 topics on the same thing.
I'll just stick to this one.

Peter

aLL DIRT IS DIFFERNT AND SO FOR ME THE DE MODE WORKS BEST BUT NOW THAT I HAVE THE LTD THE BP MODE IS WHAT I WOULD USE BECAUSE OF THE AIR GAP I THINK...NO I KNOW THE LTD IS THE NEXT STEP FOR THE F75 AND THEN NEXT MACHINE WILL BE A LOT DIFFERENT.

FISHER MAY TAKE IT TO A WHOLE NEW LEVEL BECAUSE I THINK OUR HOBBY HAS NOT CHANGED MUCH OVER THE LAST FEW YEARS.. TOM KNOWS EVERY TRICK IN THE BOOK FOR THIS MACHINE HE HAS A MIND FOR TESTING AND HAS SAVED ME A LOT OF TIME I ALWAYS TRY OUT HIS IDEAS AND TESTS AND SAY WOW I WOULD HAVE NEVER FOUND THAT OUT WITH OUT HIS HELP..

THIS IS THE BEST FORUM FOR INFO SO KEEP READING THERE IS A LOT OF INFO HERE AND GO BACK A FEW MONTHS IT GETS EVEN BETTER!

LowBoy

TAKE A LITTLE TIME KICKBACK AND WATCH SOME OF MY DETECTING VIDEO'S BELOW ON YouTube

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Peter,

pf = Is a timing circuit that reduces reportings of 'slow target changes' like a clump of mineralized dirt vs. a smaller/distinct sharp-responding target (strong or weak).

bp & cl is a longer sample-rate.....more samples/snap-shots (read = slower responding) mode/process that allows.....especially for deeper/fringe targets...to be analyzed more times, thus increasing accuracy/reporting.

Yes, Disc 5 - 20 allows for 'reasonable hunting' vs. overdrive/steroid mode(s).

Tom,

Clumps aside, would not disturbed ground exhibit a faster changing ground signal as opposed to settled (more homogenous) ground?

When you say a timing circuit are you referring to the amount of filtering?

How big are those clumps anyway? LOL Just kidding on that one.

Tom Z

Yes, disturbed ground and clumps give a faster 'target' response vs. even/level/smooth ground.......BUT ....disturbed ground/clumps are a slower 'timed target' vs. a true metal target such as a button/coin/ring/tab which are MUCH quicker.....more 'sharp' ramp-up & ramp-down. It's not so much 'filtering' as it is a electronic timing circuit that 'pf' mode employs......although/however; filters do work on the principle of a timing derivation.

Ok thanks Tom, that clears op a lot, but also brings up more questions.

The way I understand it from your reaction is: DE is somewhat tuned-down between 5 and 20 (not tuned-up from 0-5 and 20-top range)

Is this the same in PF mode?

And if so what would be a situation to prefer DE over PF, because the PF logic then seems preferrable to me in most situation?
(I've also seen an airtest on another forum that gives PF a depth edge over DE, do you agree on this fact?)

Did you find you need to adjust sweepspeed for BP/CL mode?

IRT Disc settings......pf & de modes respond exactly the same. It is only a timing response that differs......and has nothing to do with Disc settings. Depth/performance between these two modes are nearly exactly the same. The pf mode does seem to work ever-so-slightly better in the real world due to uneven terrain; hence, giving a very slight edge in depth performance (stability) over de mode. So slight.....it's hard to measure.

bp mode.......I never adjusted my sweep speed.
de mode.......does indeed require a 35% reduced sweep speed compared to bp mode.