While making some measurements with an MFJ-259B impedance
analyzer this evening, I noticed some strange behavior. The burnt
plate choke I was sweeping looked like a Hi-Z (Z>650 ohms) over
most of the HF spectrum except for the region c. 16 MHz, where
the choked looked something like 200 + j 500. Thought that this
might be a problem with the analyzer, so I removed the choke and
replaced it with a 330 ohm carbon resistor. The 259B read c. 330 Ohms,
R + j 100 over most of the HF spectrum. This seems a little strange
as I would expect the reactive component to vary linearly with
frequency. When I replaced the 330 ohms resistor with a 68 ohm
resistor, the readings became more believable (e.g. ~68 + j 2). Any
idea what could be causing this constant reactive offset at high
R levels?
Thanks,
Mike, W4EF
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