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Old May 15th 09, 04:52 PM posted to rec.radio.amateur.antenna
Jim Lux Jim Lux is offline
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First recorded activity by RadioBanter: Mar 2007
Posts: 801
Default Conjugate Match and Mismatch Attenuation

dykesc wrote:
1. Does achieving a conjugate match via a transmatch between the
transmitter and line do anything to reduce or eliminate mismatch loss
in the line? In other words, if a line is 8:1 swr into a complex
impedance load are the 8:1 "mismatch" losses still occurring even
after achieving low swr with a transmatch?

2. (Unrelated to first question) After installation of a choke at the
antenna input, swr on my off center fed dipole is surprisingly flat
across the amateur bands, never rising much above 8:1 and this only on
the high end of 80 meters. Reading Maxwell's "Reflections" series, it
seems that this may be due to saturation of the choke at higher
frequencies and I may have introduced non negligible loss into my
antenna system. The choke was made by winding my RG-58 coax through a
3" toroid of unknown permeability (14 turns). Other than the toroid
being solid black, I can't tell you anymore about it. I am using an
MFJ-259B for measurements. It would seem to me the 259B would not be
capable of delivering enough power to saturate the large toroid so
maybe my "too flat" readings are occurring due to something else.



You can use your 259 to measure the permeability of your toroid, and
infer what mix it is.

Measure the inductance of an inductor with a few turns on the toroid.

From that, you can get the inductance factor.. a few minutes searching
the catalog will probably find a match, given the physical size.