On Mon, 28 Jul 2008 13:37:27 -0400, Harold Mandel wrote:
>Then why do chokes burn up?
Because they are badly designed, and thus don't sufficiently limit
the common mode current!
>For instance, the RF Store has a pretty comprehensive
>selection of current baluns
Do any of them specify their common mode impedance vs. frequency?
>and voltage baluns.
Voltage baluns are TRANSFORMERS, not chokes. Transformers cause
the core to carry the entire transmitter power. Any loss in the
core burns transmitter power.
>They make pretty sure that each and every advertising
>page and individual model ads say something about the
>SSB - vs - RTTY ratings, and explain further that the
>chokes heat up.
See the tutorial discussion, choke designs, and measured impedance
data for those chokes in
http://audiosystemsgroup.com/RFI-Ham.pdf
You can build a FAR better common mode choke than you can buy.
73,
Jim K9YC
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