Kinda close but not exactly.
I was comparing my F75 LTD2 to my friend's non updated LTD. We put them on a bench and with a wooden ruler, would measure where each machine would detect various items out to...at different settings.
My unit, in comparison to his in both disc and all metal, was approx 4 inches off with stock coil. This was if my machine was in the DST mode. Even on my machine, there is approx 2 inches difference between the non DST and DST...or simply 9.0 and 9.1 modes. Fisher said the 2 inches was typical depth loss between the two modes. But my unit with DST not engaged, was still off about 2 to 2.5 inches compared to my friend's machine in disc mode...and even more so in all metal.
We put my stock coil on his machine and by doing so, his unit did NOT act up or go erratic. His machine lost around 2.5 inches of depth compared to the other coil he had.
So this sort of explained why his was hotter than mine in disc mode. BUT does not explain why the bigger difference in all metal. My reasoning is that the all metal side is just weaker. It's smooth...where as his was very erratic. But I think my particular unit and a lot of the 11-14 machines had this particular problem. Those that do not hunt in all metal wont notice it and might be happy with the performance in disc mode. I hate disc mode...and anybody that runs a F75 knows it is famous for having a very inaccurate target ID system...in which it will lump a lot of non ferrous items into the iron category. Which means you'll simply walk right over a bunch of good stuff by running in disc mode, even with just enough to knock a nail out. Anyway, if you have ran the 75 for long, you know that it has a boost/amplifier that kicks in when the sensitivity goes over a certain point. I think in all metal, it is anything over 39 sensitivity. Don't have the manual out in front of me but that seems to be right. From 40-99, the boost is enabled. On my particular machine...I think the boost was not engaging. It was basically the same performance from 30 to 99...no real change. Whereas on my friend's machine, there was a pretty big jump in performance.
When I called Fisher and told them my problems, they thought my coil was bad and wanted me to send it in...WITH my unit. If the coil was bad...I think they could have just sent another coil to replace mine with. Instead, they requested my machine to be sent in. Which tells me they probably know there is a problem with early run units, and they are correcting them without trying to cause a big fluff or scare. I'm betting they are gonna send mine back and say it was just the coil...when really they are gonna reload the software to the newest version and correct the real big issues. We'll see. It's down there right now. I had time to take a bunch of performance notes before I sent it off...and will compare when I get it back.
