Do I need to include the coil cable when calculating impedance for the coil?

[kac]

I am still working on the 5x10 concentric here. Figured out the stock coils included the cable for impedance an resistance and my coil has similar impedance and resistance without the cable. Cable is adding 2.1 mH over a 6' length.

Frequency on the coil is pretty much spot on right now.

Do I need to factor in the cable on this to get it to work properly? Curious because Tesoro used to sell coils with either 3' or 5' cable lengths and also offerend 5' cable extenstions. My thought is that must impact performance of the coil right?

[Carl-NC]

In a VLF it's not as big a deal as PI. The TX coil is usually resonated with a relatively large cap so the cable cap makes little difference. On the RX side the same thing, and with some models there is no resonant cap at all so the cable cap just shifts the SRF a little. Again, not a real big deal unless it shifts the RX phase enough to alter the GB point. Usually won't happen. The little bit of additional cable resistance slightly de-Qs the coils so the power loss goes up very slightly.

[kac]

Thanks.
Should I refigure my winds so my coil is closer to the stock coils that were measured with cable in place? Talking 1.8-2.1mh added to mine with cable. Right now when I test the coil has poor performance.

Still haven't solved the constant sound in all metal mode either but thinking I could be way off on my winds.

[Carl-NC]

When you say "1.8-2.1 mh" do you really mean "millihenries"? Because a cable won't do that.

[kac]

Yes milihenries. If I measure just the cable, even the stock 5' extension I get a 1.8mH on ground sides and 2.1mH on the others. Attached to my coil they are + 2mH approx.
Sorry for the noob questions on this.

[Carl-NC]

You're doing something wrong. The cable will add almost no additional inductance to the coil, typical values for coax are less than 1uH/m. Might help to show how you are making your measurements.

[kac]

I have been measuring with smart tweezers. Here is my setup:
I have the Delta female connector on the cable so I can connect directly to the Tesoro and have been reading from the leads. I did cut the cable down to 1ft just for testing purposes and made no difference. Previously was a 6' length.

Sorry for the delay in replying back, for some reason my posts where not being posted.

[Carl-NC]

I still don't know exactly how you are measuring inductance but if you measure a raw coil at, say, 1mH then adding a cable should not change it by more than 1%. If it does, then either you are not measuring what you think you are measuring or the hook-up is wrong.

[kac]

Thanks