Search Coils

[Anonymous]

Eric (or Mr Bill)
The Aquastar is described as having 'a grounded stud search coil'.
What is this and do any other of Erics designs have this feature ?
Brian

 

[Anonymous]

The stainless steel stud on the top of the Aquastar coil is connected to the coil shield and grounds the electronics to the sea water when immersed. This may seem a strange thing to do, but there is considerable evidence that it reduces noise. I first noticed this when working at sea with a large boat towed coil. The lower end of the coax (3/4in diameter in this case) snagged on a coral head, which stripped off some of the outer jacket. The braid was then in direct contact with the sea water. The noise level on the chart recorder reduced considerably, but the detection range was not affected.
Terry Crenshaw has noticed a similar effect in Hawaii, where a ground wire from the electronics housing on a CS7, and run down the shaft to the sea, reduced threshold noise considerably. What the source of the noise is that it reduces is not clear, but the evidence points to external rf pickup.
As Reg Sniff has found in his experiments with DD coils, any reduction in noise level is beneficial as it enables those faint signals to be heard more clearly.
Eric.

 

[Anonymous]

Thanks Eric
No direct benefit to the wet sand machines then at present.