K9YC's RFI-Ham.pdf file is an older one with a lot of good information, but K9YC wrote the 2018Cookbook.pdf paper specifically to update the information on common mode chokes.? He no longer uses some of the information in the earlier paper, and he now strongly recommends only #31 for common mode chokes for any of the HF bands.
Type 31 ferrite was specifically developed by Fair-Rite to have the kind of internal loss at HF that the other cores don't.
73,
Dave? AB7E
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On 1/27/2020 9:43 AM, Randall Steffens II via Groups.Io wrote:
I think Dave meant to link this document by K9YC - . It¡¯s the one where he compares a number of different types (#43, #61, #73, #78, etc) and why he often prefers #31. But he has good things to say about #43 as well! Also #61 and #73 in some circumstances. This document is a GREAT read!!
Randy
NC8U
