Been a while since I looked at the pin outs when I was fixing a short in the 12x10 I bought knowing it wasn't working, so I'm going from memory here. Somebody correct me if I'm wrong as this is just off the top of my head from vague memory.
If I remember right there were two wires for the TX (transmit) winding, then two wires for the received signal from the RX winding. So that make's 4. Then there was a redudant ground that I *think* some of the early coils used for some odd reason way back in the day. And then there is the meter ID output which makes 6 pins. The redudant ground was eliminated early on in the coil wiring and the meter output ID pin isn't needed in the coil's cable, because that extra pin only outputs from the control box back down the meter's coil cable to the meter to read and display the conductivity (voltage) of the target on I think a 2 volt scale generated inside the control box. Think about it. The coil plugs into the meter, so there is no need for that ID pin between the meter and the coil, because the ID output voltage travels from the control box only to the meter, so that extra pin only exists in the meter's cable between it and the control box.
Any meters that don't have their own battery draw their power from the TX output in the coil cable. Some might think this means the TX winding is getting less power, but in reality the meter is drawing it's power in parallel to the TX winding, so both are still seeing full voltage. I have heard some in the past claim not using a meter might give the coil a bit more output power but in reality I don't think that makes any difference. If the meter was wired in series to the TX winding then sure, the TX winding would be seeing less voltage since it would have to pass through the meter first. But in terms of the meter being wired in parallel like it is, the only way that could possibly give weaken the detection field generated by the TX winding would be if the Sovereign was being taxed trying to handle the amp draw of both meter and the TX winding, but the amp draw is so very tiny that I'm sure the Sovereign was designed to be able to handle the ever so slight amp draw of both without sagging in the current being delivered to both.
Let me see if I can dig up an schematic to post here...
Oh, and far as shortening the coil cables...I've read where some have been told by Minelab that it really won't improve performance. Probably partly due to the pre-amp boosting the signal at the RX winding before sending it up the coil cable, so it's stronger and thus less prone to EMI or weak signal degradation. The pre-amp circuit in the BBS machines is one of their unique features that probably is one of the reasons they are so deep and also run so smooth. By doing an initial boost of the very weak received signal right at the coil before it's had a chance to pick up EMI or degrade while traveling to the control box, that should make the machine run smoother and get deeper. Once the signal reaches the control box your sensitivity control determines how much more to amplify the signal based on where you set it. There comes a point where too amplified of a signal is boosting too much noise or ground signal and the machine can no longer sort out what part of the signal to pay attention to (the target), versus what to ignore (EMI and/or the ground signal).
Many people think the sensitivity control adjusts the output power to the transmit winding in the coil. It doesn't on most machines. Some can adjust that (such as some Whites), but IMO the benefits are a wash. In most situations a certain static setting of the TX power provides the best performance in most soils/sands, which is why it's set and can't be changed at the factory on most machines. Too much power to the TX winding and it starts having issues with balance between it and the RX coil, and also can have major issues with the ground matrix. Which is why some said Shaun's amp (which increased voltage to the TX winding) was unusable in their soils or sands.
By the way, the pre-amp on the RX winding is pretty much unique among BBS machines. The FBS units don't even have one far as I've been able to dig up. Only detectors I know of off hand that also have a pre-amp in the coil are the Xterra line. Haven't run across any other machines yet that I've seen have one in them. Remember that putting that little pre-amp circuit in the coil is added expensive in manufacturing. A typical coil doesn't have any electronics in it, but rather just two windings (TX and RX) and maybe a capacitor or such, but that's about it.
I remember Ralph from Sun Ray saying something about most (or at least some) Sovereign coils not even having RF shielding in the cable, unlike most detectors. I would figure that's probably because of the pre-amp making the RX signal more robust and so less prone to picking up EMI traveling up to the control box. I think he said the newer versions of the Sun Ray S-12 coil (they have a different cable color, see coil sticky for details) do have RF shielding because they needed to use that kind of cable anyway to build the FBS version of that coil.
There's been debate as to shortening coil cables making the Sovereign run better/deeper. Two things could make that possible- shorter cable = picking up less EMI in certain environments, and shorter cable = less wire resistance so less voltage drop from resistance in the wire going to the TX winding. But, both of those things are so miniscule and hard to measure in the lengths of wire we are talking here that I doubt either is a real issue that you could even measure or notice. The only one I think might show it's self would be the less EMI thing if you were hunting right around a bad source of it such as a house or something. In that case a shorter wire might show visible results. Also, wrapping the coil cable around the metal shaft on a dector creates an inductor, which can resist current flow, but again there is so little power traveling through the coil cable that I doubt it's something you could even measure with fine instruments, let alone notice in performance.
If you were to say add 10 or 20 feet more coil cable to your detector then that's probably where you might see issues with wire resistance, inductors resisting current flow, or EMI problems that you could really see performance degradation from.
All that said, would I shorten the coil cables on my Sovereign? Sure, why not. Way I look at it it can't hurt and *might* help in some small way in certain situations. But people have to remember that if they do that they won't be able to hip or chest mount for land hunting (unless they are using a meter on the shaft still since the coil only has to reach the meter and then the meter's cable will reach your hip or chest mounted control box), or say to chest mount for water hunting. That could hurt re-sale value of your coils. Then again, somebody could easily buy a plug in coil extension cable to do those things, but for water hunting if the coil's plug is near or under the water then it's out for that.
Since I only use my stock 10" Tornado on my water shaft, I'm thinking I might shorten the cables on my S-5 and 12x10 just long enough to reach the control box, so that if a meter isn't used the coils will still reach the box on the shaft. And, I might also shorten the cable on my Minelab meter too, because that's also got a ton of extra cable on it for somebody leaving the meter on the shaft but hip or chest mounting the control box. Come to think of it that does bother me. If not for the EMI or other issues above, then just for that fact that it's all that extra bit of weight on my homemade light weight shaft. Maybe a winter project to shorten my coils/meter I think.
It's not an issue with Ron's meter, since he doesn't use a long bulk coil cable but rather a thin one to run from the control box to the meter. One of the big perks about his meter. I like his meter better than my Minelab Digisearch meter but I've been keeping it off my shaft for now as I'd rather beat up the Minelab meter in the woods I'll be hunting this winter and want to baby his for my more "pleasant" hunts in the summer in open parks and such.
One final thought- If anybody is going to shorten their coil cables I'd only shorten it so far that it will still reach the control box mounted on the shaft, with an extra bit of length to wrap around the shaft about three times or so so you've got room to cut off cable and fix a short should that happen down the road. That way somebody can still use the coil with the control box mounted on the shaft but no meter for re-sale value and have a bit of extra cable to spare for cutting out and fixing a short. If they ever want to hip or chest mount the control box and aren't using a meter on the shaft to provide that extra cable, they can always buy a plug in extension, but for somebody chest mounting to water hunt it might be a deal killer since the cable connector would probably now be dangerously close to the water level maybe.
You've got me thinking now about shortening all my coil cables and the Minelab meter's cable. The only cable I think I'll leave stock length is the 10" Tornado, so that's on my water rig. I still might shorten that cable only long enough to reach the control box on my back shaft extension where I mount the control box to keep it high out of the water. I'm still mounting it there when I get the waterproof Planno box, because that way it won't try to float or bang into me and offers less water resistance. Right now the plastic bag I'm sealing the control box in back there is working nicely at giving me extra confidence my GT won't get wet.
PS- There was a thread a few months back in the modifications forum discussing the shortening of the coil cables on detectors and whether or not that might increase performance. I go back and fourth on the issue due to how Minelab is boosting the RX signal, but like I say it can't hurt and *might* help due to the issues discussed above (and also in that thread), so if you are handy with a soldering iron and heat shrink why not? Plus it makes the shaft look less cluttered and drops a bit more weight off the machine. Be sure to shrink wrap each wire and the shrink wrap the entire mass of them to the outside cable insulation well so that there are no potentials for shorts or water contamination say on a rainy day. If you are soldering right to the coil plug's pins on the back of the connector be careful about applying too much heat because some of those plugs have very little metal between where the wire solders to and the actual pin connector inside the plug. I had to knock 2 or 3 of those pins out on my SEF's stock plug and replace them with pins from a similar plug at Radio Shack (they don't sell plugs with the right number of pins but they are using the same pins in them).
