Originally posted by DrStiffler
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I agree it is no good with the renaming of L1 to Lb, especially when the remaining coil numbers are also changed. To avoid confusion this ought to be corrected or removed.
You write: "collector coil L3", I guess you mean L2 ?
So
L1 is the coil related to the base of the transistor
L2 is the coil between collector and the positive supply.
L3 goes to the AV plug
In the SGate case:
L3 is between the two outer tubes
L4 is beween the middle of the inner tube and AV the plug.
My frustrations are about RF coils in general, as two coils with the same inductance measured with a LC meter, but different geometries does perform the same.
So to repeat myself, I'm in serious lack of experience with RF coils. I guess I have to make a lot more different coils to get the touch of it.
As this is very time consuming the specs of your coils could be a great help to gain more understanding as I guess you have selected the best compromise .
I have had both the basic SEC and the SGate running with relatively decent results, but this is too much trial and error for my taste. Thats why I want a collection of coils to learn more, knowing that many will be for no use when the experiment is over.
My new Sgate is:
inner tube 15mm diameter 130mm long, capacitance 15pF
As somebody stated (free from memory)
Time is a great teacher, but eventually the cost is ultimate.
I found this calculator on the web. With this it is possible to get an idea of the coil specs.
I have now the formula in my spreadsheet and extended a bit for wire length and DC resistance.
Martin E. Meserve - K7MEM - Single Layer Air Core Inductor Design
Eric
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