What's a "salt coil"

[Anonymous]

How does a salt coil differ from your average coil, I hear they can deal with overhead powerlines and such, they lose some depth in the process, but I'm curious how the technology is different? Do they use farraday shielding? I have seen this shielding on some "How to build a coil" papers, though my Explorer coils don't seem to have this.

 

[Anonymous]

Are you talking about a salt coil in regard to a PI or in regard to a VLF. For PI's it was discussed a bit in the POSTs below. In regard to VLF's they used to have coils they considered coils for use on Salt Water Beaches I don't knwo if they called them salt coils or not. But they were Coaxial Coils and were able to handle the salt and mineralization better than Concentric Coils. They were also very good at eliminating outside electrical interefernce. On the downside they were very heavy and quite bulky. Hope this helps.
HH
Beachcomber

 

[Anonymous]

Hi Charles,
There was some info about the Salt Coil some time back on this forum.
Basically, a salt coil has a xmit coil that is mono type xmit coil and the receive coil is something called a figure 8 coil. This receive coil is basically two coils because of the figure 8 design. Actually, one can build a single figure 8 mono salt coil also. However, this design doesn't not eliminate the ground response like the separate xmit and receive design does.
I have built one and yes, they do eliminate much of the external noise like the noise generated by power lines.
Because of the size of the smaller receive coils, they do have reduced depth capabilities, but are normally extremely quiet.
I tried the coils both shielded and unshielded. Unfortunately, I really didn't spend that much time using either one so I cannot tell you if there were disadvantages to the unshielded type.
On a regular PI, one of the receive coils will give you a positive response and the other a negative response when the coils are passed over a target. There will be a slight null when the target is between the two receive coils.
Reg