[TowerTalk] Common-mode choke

[Steve Hunt]

The OP asked about a 10m choke. Take a look at the Fair-Rite complex 
permeability charts and you'll see that at 10m the ratio u'/u''for #61 
material is 1.3 - that's a _lower_ ratio (lower Q) than #31 at 160m or 
#43 material at 80m.

I wouldn't recommend #61 for lower frequencies, but the OP specified 28MHz.

Steve G3TXQ



On 20/05/2014 08:09, Jim Brown wrote:
> Nor do I, but the #61 chokes I've measured are in the range of 4-5. 
> Compare the data sheets at the beginning of the Fair-Rite catalog for 
> #31, #43, and #61. For the first two, u'' is greater than u' by a 
> factor of about 1.6 in the range of 30 MHz, while for #61, the 
> relationship is the opposite, and by a similar ratio.