[TowerTalk] Ferrite Cores in Trapped Dipoles

Bill Turner dezrat at copper.net
Wed Feb 7 12:31:26 EST 2007


On Tue, 6 Feb 2007 19:10:58 -0500, "Dan Zimmerman N3OX"
 <n3ox at n3ox.net> wrote:

>Yet many of us are using autotuners (which all have powdered iron
>inductors) on pathological matching cases, probably with high
>circulating currents.

------------ REPLY FOLLOWS ------------

Yes, it can be done but doing it right requires some careful
engineering. It's not something you want to slap together in a couple
of minutes and put up in the air.

I still maintain that the best traps (i.e. lowest loss and most
reliable) have cores made of nothing but air. Also, the only
capacitance present should be the self-capacitance present between
turns of the coil. A trap like this is a bit harder to make because it
requires considerable cut and try trimming to achieve resonance, but
once made, will work without problems for years on end.

Bill, W6WRT

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