If you think the wrong questions are being answered it's because those
formulas assume that you either know or want to know the amount of
inductance you need or have. There is no way any of those formulas are
going to tell you how much inductance you need to resonate any
particular antenna.
And what don't you know, or can't easily find out, about #8 gauge copper
wire from a big box store? Dimensions and resistivity are available in
hundreds of places online. It's even pretty easy to estimate the Q of
such a coil, at least closely enough for most needs. I could probably
even come up with a good estimate for the stray capacitance without much
effort.
I think it's pretty unreasonable to expect a single formula to account
for every possible real world scenario, the expectation being that you
know how to apply the right formulas for the task at hand.
Dave AB7E
On 2/27/2019 12:35 PM, terry burge wrote:
Hey folks,
I look at these coil calculators and come to the only conclusion is the wrong
question is being answered. Example:
If I have 130 feet of 12 gauge multi-strand insulated house wire (from Lowes) how
large of 3-4" coil wound on a PVC form do I need to resonate it at 1830Khz?
1850Khz? 1880Khz? 1920Khz?
Or using a commercial coil from what I believe was an AM broadcast station like
pictured on my qrz page? (qrz/KI7M)
Or if you are real ambitious using some small Aluminum tubing from
DXEngineering or similar source?
These coil formulas always seem to want some factors that may not be known about using
the available material like 1/4" or 1/8" copper tubing. Or number 8 gage copper
I see in the local Lowes or Home Depot. And how to get something silver plated once out
of high school chemistry class I don't know?
Just a thought or two.
Terry
KI7M
On February 27, 2019 at 7:26 AM "Richard (Rick)
Karlquist"<richard@karlquist.com> wrote:
This may be helpful:
http://hamwaves.com/antennas/inductance.html
Rick N6RK
On 2/26/2019 9:06 PM, Gedas wrote:
Once upon a time I found a site that had an awesome online calculator
for calculating the inductance of single layer coils where you could
Gedas, W8BYA
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