Got a question on coil cords!

[Joe Kononchik]

Does the length of the cord effect the performance? Does it change the depth on targets? Does it change the signal responce time? Does it change the timing? Thank you for looking,Joe

 

[Tony]

Joe,

I am very confident in saying that a change in cable length will have a negligible effect on PI operation.
Something maybe measurable in a lab but I think that would be the extent of it.

Tony.

 

[Ken~Digs]

Hi Joe & Tony - I Shorten Cables sometimes just to Clean up the Mess on super long cables just for less Bush Snag & Asthetics (Looks & Feels nicer) Resistance would not be an issue of Any kind at a length of 10' or less . Ken

 

[Bob_T]

I know this is a fairly old thread, but here's a link to BBSailor's paper on making fast PI coil. There's a couple of paragraphs on cable length and I think his view is that cable length does have an impact, at least for a fast coil design.

Making a Fast Pulse Induction Mono Coil

 

[bbsailor]

I know this is a fairly old thread, but here's a link to BBSailor's paper on making fast PI coil. There's a couple of paragraphs on cable length and I think his view is that cable length does have an impact, at least for a fast coil design.

Making a Fast Pulse Induction Mono Coil

Bob_T and all interested

The coax cable adds capacitance to the PI coil circuit. Typically, it adds about 30pf to 35pf per foot. The optimum value of the damping resistor is based on the total capacitance of the coil circuit. If you can reduce about 100 pf capacitance by reducing the cable length about 3 feet, you can use a little higher value of damping resistor and thus sample about one microsecond faster. This allows you to detect smaller targets better because the coil discharge time constant is controlled by the coil inductance divided by the damping resistor value. Shorter coil discharge time constants allow smaller targets to be detected better. So, depending on what you are looking for, it could make a difference.

I attempted to write the article to cover most common questions and cable length is just one of those common questions along with all the other factors that contribute capacitance to the coil circuit.

bbsailor

 

[Sven]

I have been keeping my coax to a length of 32-36" depending upon if I am using a s-handle or under the armcuff mount control box.
Your write-up was excellent and helped produce my fast coils........saved it as a pdf. file that I share with others.