Coax for duel field coil

[PVGOLD]

Hi Terry
Long time no reply. Been working 12-14 per day. When I made a duel feild
I used a piece of the coax to decide size, then subtracted to allow for plastic wrap, shielding etc. Now I was making a folded 8 cunfiguration. I found that
folding the bundle did not change inductance. When I wond the coil inductance was 345 when wrapped per Reg's instructions inductance ended up at 305. 8 in id. 27 wraps, 24ga silver 24 strands. Teflon insulation.
I bench tested it seemed fine, that's as far as I've gotten. 1 day off in 5
weeks, 8 more months and I will be a part timer! I have although been following your posts. Sounds like you've got it down, and enjoying it at the same time.

Best Regards

Herb

[Roughwater]

Herb,

Wow, one day off in 5 weeks. Sounds almost like slave labor. I've been there but not quite to the extent you have. If I may ask what industry are you in? I hope they give you a little more time off than what your having to deal with right now.

I've made a few coils now but really haven't used them in the field yet, just a little back yard testing. I have a few irons in the fire and the wife likes to keep me busy also.

Sounds like you are doing well so far at builing your coil. I also noticed that the inductance doesn't change much from a round mono when converting to a duel field mono configuration. As to figuring the length, I did the same as you using coax but I think when I wound the coil I put a lot of tension on the hooks and eyes causing them to flex or turn slightly and came up a little short on a couple of coils. They are now my expiermental coils for the moment.

Take it easy,
Terry

[Mark-VA]

Hi Herb,

Here is a little different concept for a dual field mono coil I built that seemed to work fine. It is different from the Whites design since it uses only one coil formed into a figure 8 concept but then modified even more.

What I do is this, I build a coil larger than the housing I will use (step 1). I then squeeze the coil into something like a lopsided figure 8 (step 2) and then twist the top part one half twist to form the 8 (step 3). I then fold this smaller coil back into the larger one (step 4) and ultimately elongate the inner coil (step 5). This allows me to use a DD type housing such as the Hay's 11" by 9" design. The larger coil fits in the outer ring while the smaller coil fits in the inner center elongated zone.

Attached is a simplified drawing of the steps I mentioned. Hopefully, it will make sense.

The idea of this design is the larger coil is used for finding deeper targets, while the inner coil will be more sensitive to smaller objects closer to the surface.

Reg

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