AN/PSS-12 Mine Detector Documentation

[bbsailor]

Hi Joe,

I have a couple of those ebay coils, plus also a full AN19/2 kit purchased on ebay a while ago. None of the coils have internal shielding and the cable doesn't have any either. I found I had problems on a wet beach because of the capacitance effect, and also if you move the cable near to the aluminium upper stem, you get a false signal. The test pin seems to be mild steel and my Deepstar picked it up just as well with a 15uS delay. Sensitive to iron mineralised ground and with only manual zeroing it was hard to keep a threshold. Not sure I would like to go mine hunting with one, particulary for low metal mines.

Eric.

Eric,

Good to hear from you.

This military machine has a very low pulse rate of 67 PPS with about a 120uS bipolar pulse to keep from setting off magnetic activators. The instructions say the coil should be moved at no more than 0.3M per second. This make clearing mine fields rather slow going.

I would have thought that the design of these coils would have been shielded as they should have accounted for the instability caused by using non-shielded coils as well as the unshielded cables that are sensitive to movement near metal. I guess they spared no expense with the lives that are at stake using this device.

The only way to make these coil usable on the beach is to get out a Dremmel tool router and open up the bottom, remove the coils and wind new Teflon wire shielded coils, shielded with Scotch 24, add an SVHS coax, and reseal the coil with epoxy.

I could probably use up to about 32 turns of AWG30 for the center coil (450uH) to obtain a little more sensitivity. I would use about 20 turns of AWG 28 Teflon stranded wire for the TX coil. With the right coil damping, this reworked coil should be able to work at beach delays of about 10us if the SVHS cable is not too long.

bbsailor
(Joe)

[Geo]

Hi bbsailor.
How are you???
Long time to read something from you....
Regards

[bbsailor]

Hi bbsailor.
How are you???
Long time to read something from you....
Regards

Geo,

I am fine and getting my sailboat ready for another season. Once on my boat, I only check this forum about once a week.

Go to this web site and download this free and very fine computer program that will be useful for making PI coils.

http://www.miscel.dk/MiscEl/miscel.html

The author wil have a refined version out soon, as he updates it about twice a year.

I use this program for evaluating coil charge and discharge curves. Make sure that on using the discharge curve you use the value of the damping resistor to see how quickly the voltage approachs zero or the time when the first RX amp stage comes out of saturation at about 5mv.

There are many features in this program that will help PI experimenters optimize coil and TX circuit performance.

You can download the program at the above web link. Make sure you read his instructions at the above web site before you use the program. Pay attention to how to enter data in various units of measure for this program to use.

Enjoy

bbsailor

[Geo]

Hello Joe.
You are very lucky if you have so many time for the boat. I have a small boat for fishing and i use it only 5...6 times per year (no free time), and one time per year i rent a "Bavaria 42... 49feet" with friends for 5...10 days. That is all. All the other time work.... work..... and detectors.
Anyway thank you for the program. I downloaded it and it looks very interesting.
I wish you good fishing
Regards