[Lowfer] a thought on coils

[Ashlock,William]

Hi John,

>The simplest coil I ever encountered was made by Walt
>Glazar, W3WI. His beacon WI was heard all over the East coast as well as
the
>mid west and it consisted of nothing more than a PVC form with two pi wound
>litz sections over a small ferrite rod. Walt was a stickler for efficiency
>and if it didn't perform, it didn't stay in his beacon. Ferrite is very
>useable if you don't saturate it with too much power provides an easy way
to
>tune a coil to resonance.

I have spent many hours trying to design loading coils using various types
of ferrite cores because they appear to offer reduced size and ease in
construction. The best Q I have been able to obtain is approx 100 at 150ma
of current. Turns out it is very easy to saturate ferrite cores. I have seen
boasts of transmitting performance for these coils from many sources, but
when it comes to the actual coil Q, at the typical 150ma antenna current,
there's always a conspicuous lack of data.

Speaking of simple coils, using Litz on a 4" PVC pipe (preferably with
slots) a Q of >300 is no problem at all. Not sure why the 'bucket brigade'
approach is so popular, except for the lower cost of the house wire. The Rac
for #14 copper wire at 185k is not really that good because of the 'skin
effect' losses. 

BTW: Do have or can you get some more details about WI's loading coil? 

Bill

   

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