Topband: MFJ 259B on 160M

mstangelo at mstangelo at
Mon Sep 28 06:39:58 PDT 2009


The problem with using a filter ahead of your "wideband" MFJ-259 analyzer is that the filter will transform the impedance of the load you're trying to measure.

You have a better chance of measuring the impedance in the presence of a strong signal. with a "narrorband" vector network analyer such as the N2PKVNA (kit) or AIM4170.

If you do need a filter both units enable you do perform a "OSL" calibration with open, shorted and 50 ohm load calibration with a filter inserted in front of the input.

In general, I find my MFJ-260 unit handy in determing the lowesr SWR but I doubt it's accuracy when the load deviates to far from 50 ohms.

If you want accurate readings I'd take a look at the N2PKVNA:

and AIM4170:

Here is a good write up on analyzer accuracy:


Mike N2MS

> Hello,


> Has anyone made an effective AM broadcast filter (HB) for their analyzer?


> I have to feel that my lack of readings on the unipole may stem from AM

> interference.

> I have a station here in town, or close on 1400khz.


> 73's


> Glen K4KV

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