[TenTec] Baluns

[Jim Brown K9YC]

On Mon, 5 May 2008 06:02:38 -0700 (PDT), Jim WA9YSD wrote:

>Voltage balun or Current balun.  With out any fancy clamp on RF 
>current meters and the sort, what are some simple things can the
>average ham can do to determine if a Current balun or a Voltage 
>balun is needed when working on different types of wire antennas 
>fed with eather coax or open line?

http://audiosystemsgroup.com/publish    

Select the first two items on this page and study them. One is a 
tutorial that covers a lot of ground, including common mode 
chokes. The other a Power Point that I've presented to a bunch of 
ham clubs and most recently at the Visalia DX convention. BTW -- I 
don't sell any of this stuff, and there are no patents. 

It was shown at least 30 years ago (by W7EL and W2DU, among 
others) that current baluns (common mode chokes) are FAR superior 
to voltage baluns (transformers). 

>Proper way of doing things is to use a voltage balun at the feed 
>point of the antenna followed by a current balun, right?  

People will try to sell you anything if they can make money doing 
it. Like $200 speaker cables and $2,000 power line filters for you 
stereo rig. 

The proper way to do things is 1) whatever it takes to match the 
antenna to the transmission line (maybe nothing) and 2) a serious 
common mode choke on the transmission line. For example, a 
resonant halfwave dipole is a good match to coax, so all you need 
is the choke. A beam may need a matching section AND the choke. 

73,

Jim Brown K9YC