Actually, ferrites are relatively inexpensive as imports go. I get them from
Mouser (great company to deal with; highly recommended). My last order was a
few years ago. For 22 x 2.4-inch #31 toroids, the average cost was US$7 each
plus $1 shipping to ZL.
73, Rick ZL2HAM
[mailto:firstname.lastname@example.org] On Behalf Of Ian White GM3SEK
Sent: Wednesday, June 27, 2012 8:51 PM
Subject: Re: [TowerTalk] Coax, conduit and toroids
The problem may be that he needs to decide right now, while he is installing
On the other hand, large ferrite cores will be very expensive imports in ZL,
so it won't be cost-effective to scatter lots of them around "just in case".
One option might be to look up K9YC's recipes for ferrite chokes using the
big #31 clamp-on beads, and make the air-cored coil at the base of the tower
when installing the coax. Very little is lost by doing that much in advance.
Later, if a "serious" common-mode choke does turn out to be necessary at the
base of the tower, then simply snap the big bead onto the coil that is
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