Maybe I can help......maybe
Does running it in either 3 or 4 tones reduce depth? If so, what's the point in having the options?
The F5 has four tone id options you can use based upon your requirements. Two of them, the 1 and 2 tone modes are VCO type audio modes. Two of them, 3 and 4 tone modes, are modulated saturated audio modes. The VCO modes are easier to hear all the way out to audio cutoff point. Threshold settings play a part in this because they affect the cutoff point audio. Threshold settings closer to the ends (+9 or -9) give a more clipped fringe depth cutoff. Threshold settings at 0 give less of a clipped response. I think the VCO modes have a fringe depth cutoff point that is at a greater distance from the coil compared to the modulated saturated audio modes AND is easier to hear.
Why have different audio modes? I'm sure many of us who use the multi tone id option detectors use the different audio modes for different purposes. 4 tone is for when you want nickels range targets to stand out from the alum trash, 2 tone is best to use around large iron. That will get you started. You need to hunt the detector in various scenarios to figure out how to make the audio mode selections work for you.
Does turning the gain or threshold up past a certain point reduce depth? If so, what's the point in having those options?
If you turn the Threshold control all the way clockwise to +9 and then turn it a little further you will see that the threshold control has a stop. You can't turn it any further clockwise past that point. Positive Threshold settings are wide open settings that also invoke a weak audio boost feature that made the tiny signals more robust. That means that the detector is open to even the tiniest EMI noise, and not only open to this noise but that it enhances this noise as well. You can get a very noisy detector with Threshold settings at 0 and above.
We found that turning the Threshold control clockwise purposefully into that 'stop' point would often put the detector into a state where the tiny EMI noise was eliminated as if a lower Threshold setting was being used, but kept the audio boost feature in play. It was like a noise cancel feature. But it is not a deliberate feature. It is just a potentiometer/software bug that we use to our advantage.
Can it effectively be ground balanced using pump mode if there is any discrimination on?
Yes, you can ground balance in the discrimination mode by just holding the phase lock button and pumping the coil until the numbers match.
Does the pump mode ground balance work correctly if when you get near the ground during balancing and it beeps at something metal? (as in trashy areas where you maybe can't get a totally silent area without discrimination).
No...metal will throw off the phase number and you will get an improper balance. You should also learn the difference between metal beeps and Phase Lock beeps. Practice so you understand what is going on when you use the Phase Lock button.
Also, if your sites FE304 bar graph is 3 or 4 bars, your ground balance will be off by using the Phase Lock method of ground balancing. When you have high FE304 bar graph readings you really need to ground balance in the all metal mode. The ground balance point is much more finite and you can't hit it with the Phase lock button. But if the FE304 bar graphs readings are below 3, the ground balance point has more spread in it and the Phase Lock button will get your into that range.
What else?
HH
Mike
