Double wire question

[Pepe LeMiau]

Hello,

Recently I got a free spool of double 0.8mm silver plated copper wires in thick insulation.
I thought I'll use it for the new "fast" PI mono design.
However, it's next to impossible to separate the two wires, because the insulation is very strong.
Does it make sense to wind 12 turns of double wire and then connect both wires in series ?

[Qiaozhi]

Hello,

Recently I got a free spool of double 0.8mm silver plated copper wires in thick insulation.
I thought I'll use it for the new "fast" PI mono design.
However, it's next to impossible to separate the two wires, because the insulation is very strong.
Does it make sense to wind 12 turns of double wire and then connect both wires in series ?

It's difficult to say, without actually trying it, whether the results will be satisfactory.
The main problem is going to be calculating the number of turns required for a given inductance. It looks like you may need to "go where no man has gone before" ... to quote a famous phrase.

[Ism]

I tried the same thing and had poor results, the windings seem to cancel each other. That is not to say that you shouldn't try it if you have the extra wire to play with. I had better results with windings in parrellel but I found no advantage with either configuration over a simple single conductor mono.

[Qiaozhi]

I tried the same thing and had poor results, the windings seem to cancel each other. That is not to say that you shouldn't try it if you have the extra wire to play with. I had better results with windings in parrellel but I found no advantage with either configuration over a simple single conductor mono.

It depends on which ends you connected together. The coils should not be in anti-phase, otherwise they will cancel.

In this particular case I think the problem is one of not being able to separate the wires, rather than trying to improve on a mono configuration. Personally, I would also simply connect the wires in parallel as you suggested.

[Ism]

I understand antiphase, but the performance suffered when properly phased also. I'm not sure why, there was no reason for it not to work properly. Either way I didn't put any effort into the attempt so there may be other factors involved that I don't remember.

[Pepe LeMiau]

Wiring in parallel is not an option, the cable is way too heavy to use it as a single wire. It's rated at 2kV so the insulation is thick and not much elastic (that's another problem).
I did a simulation, basically wiring the two wires in series makes a dual field coil with both coils of the same radius placed one on top of the other.
The magnetic field seems to be not much different from standard mono. However I have no idea about target response.

My guess is that inductance won't differ too much from mono and perhaps that could be proven with calculations, however I don't have enough skills to do that.
Instead I'm going to wind 2-3 turns more than needed and I'll use inductance meter, removing 1-2 inner or outer turns won't be a problem.

One of my first PI coils (the one shown in avatar) was a "solenoid" type, it had a 1 layer with 24 turns, the overall height was ~1,8cm. Technically that's like 24 1-turn coils placed one directly on another and wired in series. It's performance wasn't bad at all, in fact it was decent compared to a couple of my later coils (although it suffers from high capacitance and can't work below 25µs). I still use it for shallow water search, because it's absolutely waterproof (and too heavy to use on land ).
If the 24x1 configuration works, perhaps 2x12 will also work, I'm going to test it soon.

[bernte_one]

it works

see here

http://www.geotech1.com/forums/showthread.php?t=17979

http://www.teknolojiekibi.com/yeni/i...hp?topic=171.0