[TowerTalk] [Bulk] Re: BALUN revisited again

[Jim Brown]

On Fri,4/8/2016 11:36 AM, Bert Almemo wrote:
> As I was reading the post I was wondering if you could use ferrites of
> different mix in the same choke/balun? Would that work or not?

It could work for two chokes in series, as shown in the CMC-230-5K. But 
since the ferrite materials are not specified for this product, it's 
hard to say what they're using. It would make sense to use #31 for the 
lower frequency choke and #43 for the higher frequency choke.

I think the power rating for this choke and the BL2006-3K may be overly 
optimistic. I've fried a similarly constructed choke on a single #31 
core with 1.5kW under heavy contest conditions with an 80M dipole. 
Plugging the equivalent circuit into an NEC model shows the need for at 
least twice the choking Z of a single choke. The second choke doesn't 
need to be at the feedpoint -- it could be well down the line.

73, Jim K9YC