[RFI] small CMC

Jim Brown jim at audiosystemsgroup.com
Tue Apr 5 19:30:38 EDT 2022


On 4/5/2022 4:21 PM, Gary Johnson via RFI wrote:
>   A secondary choice is a 1.4-inch mix 41, Fair-Rite 2643802702. Those are in stock.

#43 material is not great for use at HF because of their wide 
manufacturing tolerances and relatively high Q as compared to #31. The 
difference is that #31 is MnZn, which has both circuit resonance (the 
winding) and dimensional resonance. The two combine to provide a much 
broader resonance. While #31 also has comparable wide mfg tolerances, 
the broader resonance makes predictable designs possible. #43 is NiZn, 
which has no dimensional resonance, thus higher Q.

I didn't come to this conclusion until I did the extensive research that 
led to the 2018 Cookbook.

73, Jim K9YC


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