[Elecraft] BL2 choking Impedence measurements?

[Jim Brown]

On Wed, 25 Aug 2010 11:19:15 -0700 (PDT), Dennis KB7ST wrote:

>I have the AIM 4170 antenna analyzer ( w5big.com ).  I could sweep the balun
>in 1:1 and 4:1 mode is you'd like.  I'm not sure it will give you the
>choking impedance but will do some checking with the designer of the AIM. 

I don't own an AIM, but I've seen choke measurements made by an AIM that had 
serious errors. A good common mode choke should have a high resistive 
impedance at the frequencies where it is used, and the AIM is best suited for 
measuring impedances relatively close to 50 ohms (that is, within 1:5 or 
5:1). It's fundamentally unsuitable for measuring the high impedances of a 
good choke. 

73, Jim Brown K9YC