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Old March 2nd 06, 07:08 PM posted to rec.radio.shortwave
David
 
Posts: n/a
Default balun spec depending on coax impedance

On Thu, 02 Mar 2006 18:56:08 GMT, Bob Miller
wrote:


Thanks for clarifying, but the question remains the same. Why would a
random length wire monopole at assorted listening frequencies always
be at nine times the impedance of the coax feed? If it is not, why the
fixed 9 to 1 ratio of the balun? Would not a variable device, such as
an L-circuit antenna tuner work better?

The device prevents the generator impedance from exceeding the load
impedance, which is a major no-no.

Rule of thumb is a high impedance source cannot be connected to a low
impedance input, but a low impedance source can be connected to a high
impedance input.

For maximum current transfer a perfect match is desired (like for
transmitting) but for receiving there's a little more latitude.