In article ,
bpnjensen wrote:

Another question on this subject - what core should be used for this
application?

Amidon, among others, has cores of many materials including 43 and 77,
both of which seem to get use in these applications; however, for RFI
problems below 10 MHz, Amidon recommends cores of J material, and my
RFI problems (while not confined to under 10 MHz) are primarily below
that frequency. Would use of J material be wise here, or for this
matching transformer would I be better using the old standbys 43 or
77, and then making lots of separate chokes from other materials such
as J?

The different core type comes from the fact that Amidon is reselling stuff
from different manufacterers. I've used both 77 and J for transformers.
They're pretty much the same. Whatever was on the pegboard at the
(then existing) local shops. Seems to work best from 3-15 Mhz, if
you want to go for higher frequencies, like CB, try a higher frequency
(lower perm.) core.

Mark Zenier
Googleproofaddress(account:mzenier provider:eskimo domain:com)