Topband: Ferrite Cores

[Jim Brown]

On 8/6/2014 8:31 AM, Carl wrote:
> 31 and 43 mix are the popular ones in the 2-30 MHz range for common 
> mode suppression; 31 wins at 160 and 80, but 43 is better in the 7-30 
> range. 

I would amend that only to say that #31 and #43 are roughly equivalent 
in the 5-15 MHz, range, #43 is slightly better above 15 MHz.  #43 is a 
bit less expensive than #31, but the cost difference disappears if you 
buy #31 in quantity.  My last group purchase of #31 2.4-in cores was for 
1,100 pieces, about two years ago. We paid about $4.

Because #31 is so much better on 80 and 160, because it is more 
broadband below 15 MHz, and because it remains effective through the HF 
range, I long ago made the engineering decision to buy #31 in quantity 
for ham HF applications.  If I were ONLY working above 80M, I would look 
at pricing on #43 in the quantities I needed.

73, Jim K9YC