10 .. 15m cable for PI coil

[Geo]

Hello.
I want to locate some iron boxes in the bottom of a lake.
Water is not clear and i can't see more than half meter, so it is not possible to work a metal detector in the water.
I though that a good way is to hang a large coil 1.5m x 1.5m in a boat and started searching from the boat. The coil will be about 10 meters into the water.
Because the boxes have big dimentions don't care me the capacitance of the cable because i"ll work with large delay (maybe 50us). I want to know if the big cable will "cut" big amount of transmitting power and if it will add big amount of noise to the preamplifier.
In other words will be the detector functional;;

Regards

[Geo]

Nobody knows?????
Eric, Carl, Qiaozhi, Reg ........

[WM6]

Geo, are you trying to do this research using magnetometer?

[Qiaozhi]

Nobody knows?????
Eric, Carl, Qiaozhi, Reg ........

I doubt the resistance of the long connecting cable will adversely affect the transmit power.
You can experiment by adding a resistor in series with a standard coil to give you an idea of the expected result. The extra resistance will of course limit the maximum current that gets to flow in the coil during the ON time. But you can compensate for this by lowering the PPS rate. Since you're searching for large iron targets, the reduction in frequency will not be an issue.

[Mechanic]

The other way to skin this cat is to water-proof the detector electronics and just have a speaker cable up to the surface....

Cheers Mick

[Geo]

Geo, are you trying to do this research using magnetometer?

It is not so easy to locate the boxes with magnetometer. I am afraid that now the boxes are 1m inside the mud. If the coil is 0.5m above the bottom then i have chances to locate them.

[Geo]

I doubt the resistance of the long connecting cable will adversely affect the transmit power.
You can experiment by adding a resistor in series with a standard coil to give you an idea of the expected result. The extra resistance will of course limit the maximum current that gets to flow in the coil during the ON time. But you can compensate for this by lowering the PPS rate. Since you're searching for large iron targets, the reduction in frequency will not be an issue.

Thanks Qiaozhi. As you write.. a tes with a resistor will show.
Time to looking for the neglected Delta Pulse.

The other way to skin this cat is to water-proof the detector electronics and just have a speaker cable up to the surface....

Cheers Mick

I see it a little composite.....