Hi Ken!

It all depends on the antenna your are going to feed with this loading
coil. My system has a capacitive load of abt. 600pf and so the coil is
abt. 2,3mH. This is realized on a flower pot with about 40cm diameter,
80 turns of insulated wire. The height of the pot is only 30cm.

If you have a smaller capacitive load, you'll need more inductance and
thus increasing the diameter of the coil-body.

If you count 6pf per meter for every vertical part of your antenna and
5pf/m for every horizontal part, you can estimate the capacitive load
very well. For calculation of L and C for a given frequency or for
dimensioning air-coils (Luftspulen), I can recommend the
"Mini-Ringkernrechner"...

http://www.dl5swb.de/html/mini_ringkern-rechner.htm

I don't remember if there's an option for the language on installation
but even if it's only in German, it easy to operate.

73

OE3GHB
Gerhard





Am Donnerstag, den 11.11.2010, 20:28 +0000 schrieb Ken:
> Hello Everyone.
> I went into  a branch of Wilkinsons (Watford), today, and saw some
> straight sided cylindrical dust bins about 0.5m diameter, useful for
> large coils?
>  
> 73
> Ken
> M0KHW   IO91TV