Effect of different cable lengths on coil performance?

[snakejim]

Is the cable length critical and part of a coil design (such as part of a tuned circuit), or can they be shortened or lengthened at will?
Thanks!
Jim

 

[UK Brian]

I've got a feeling that the length is important with at least some of Eric machines.
I trimmed a little off the end of my Deepstar 2's lead as it was starting to breakdown after many years of flexing. Compared with a newer coil the trimmed is not quite as good but other changes have been made in the meanwhile such as the type of cable and the shielding of the coil so its hard to tell.
Eric is going to make me a new coil. I thought this would be better than having the old repaired as I like to have a spare for backup.

Brian

 

[Mr.Bill]

The capacitance and the resistance of the coil cable has to be taken into consideration as a total value of the coil.

Depending on the exact particulars, chopping off a lot of cable would change the way the electronics looks at the coil. Adding length would affect it also.

Now in reality I have chopped fairly good sized amounts off of cables in order to permanently pole mount the electronics box. The need to get rid of excess cable length was there. I have not noticed a drop off in performance, although it could happen depending on the unit.

Mr. Bill

 

[alton]

That has me wondering if short cable to the switch box of the Sunray probe changes the capacitance or resistance on the detectors it is attached too. If so, and it was significant enough to affect performance I would think Sunray would try to compensate for it.

Perhaps they do in the box.

 

[snakejim]

I was sure that it did matter. Just needed affirmation.
Thanks a heap!
Jim

 

[Mr.Bill]

Your comparing apples to oranges. PI detectors to VLF type.

SunRay does not make probes for PI detectors. there are designed for VLF discriminating type units.

 

[Mr.Bill]

n/t

 

[Gulf Hunter]

Lemme tell ya a story, but it's not PI technology, but could certainly apply to PI, as well. I am a water hunter 100%. Everything I own gets stem mounted in one way or another, for equipment's sake. In my opinion, it's just easier for the units to take the pounding of the surf mounted to the stem. My Excal had several unruly wraps around the stem, so the last time in for warranty repairs, I asked the tech if he would mind shortening my coil wire to 40". The control housing is mounted to a Lightening Rod straight shaft. This allowed for an aestetic clean-up and I had a couple of gentle wraps around the stem and a coil relief loop. Upon reentering the water, I noticed AMAZING sensitivity and stability gains. Thought the unit was just tuned better, but got to talking to others on the Excal/SOV forum and discovered that this was actually a performance mod, but it did not start out as my original intention. I have since had Mr.Bill perform the same mod on the GQA2, but it was already almost too deep and sensitive for me to handle already! I am convinced it is a very good idea, if done by a professional. I would never attempt to mod it myself. GH