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Old September 2nd 07, 11:22 PM posted to rec.radio.amateur.antenna
Owen Duffy Owen Duffy is offline
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First recorded activity by RadioBanter: Dec 2006
Posts: 1,169
Default making a common mode filter

Ed G wrote in
.95:



That is a good point. I'm not even sure of the vendor of the
numerous



After some additional Google research, I found them. Made by
Fair-
Rite Products Corp. PN is probably: 2643806402. Product description
matches unit on hand, and lists it as type 43 material with a Z around
where I want to operate of about 20 ohms.


My guess is that you got the 20 ohms (for an unstated intended frequency
of use) by extrapolation of the published data from 10 to 250MHz. You
probably also read that the core material is recommended for 25 to
300MHz. Both of these would suggest that the material is not the best for
your intended frequency, whatever that is.

So, for an effective choke, you may need 25 to 50 of these things. They
are only a half inch long each, so that is just 13 to 25 inches in length
in total, not unusual for that type of choke.

Owen


Ed