Nautilus coils

[Don Bowers]

Anybody want to guess (or comment) on how the coils are arranged in Jerry's patent for the Nautilus feedback method posted in the patents section of this site?? There is no mention of a bucking coil or 4B coil design.

Thanks..
Don

[dbanner]

Don, after 13 years, I will hazard a guess 'cause I recently have tried to copy the dmc-2b.
I looked at the Tyndal patent for answers and lo and behold, Jerry actually described the coil in detail, no. Of turns, taps, etc. Except....no clue as to bucking(feedback)coil, or how nulling is achieved. He specifically mentioned setting up the Rx for 0 degrees phase shift however. The feedback system of pots used to change phase of Rx with respect to tx. But no mention of nulling.
My guess is that the 40-10-10-40 tx windings with center tap, the 10-10 windings on either side of the center tap are the feedback windings. A somewhat similar coil would be the Fisher 1260x.
The aquasound uses the Nautilus coil and feedback system as well. 4b coil is out of the question, as pics show coplanar arrangement.
Without bucking coil, then how can a null be achieved in concentric setup? Surely not with just feedback system described in patent, although it does describe feedback of phase and amplitude as well.
But I guess you opened up a dmc 2b coil subsequently and you forgot to let the rest of us know.

[homefire]

I have a Decrepit Nautalis DMC II here someone could talk me out of .

[dbanner]

Poor thing has seen better days.
The Nautilus coils are balanced in FULL resonance (not "OFF" resonance like the TGSL) and 0 degrees phase shift at null, just in case someone else is curious to know.
Kindly post photos of PCB if you can.
I'll put pcb trace of metal detector Aquasound.