Topband: MFJ 259B on 160M

[mstangelo at comcast.net]

Glen,

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:

http://www.makarov.ca/vna_payment.htm

and AIM4170:

http://w5big.com/


Here is a good write up on analyzer accuracy:

http://www.makarov.ca/download/vna/VNA%20comparisons.pdf


73,

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