[TowerTalk] Testing Antennas

[Don Hall]

Denis,

I live about 2km from a 10kw AM station on 1620 kHz so have been trying
several fixes to improve my antenna measuring ability.

Your suggestion for the use of a high pass filter after the MFJ antenna
analyzer works ok if you want to measure only around 50 ohms. At both higher
and lower impedances the filter introduces its own characteristics into the
measurement and you can get some pretty strange readings.

The filter only acts as a low pass element when it is properly terminated in
the design impedance, usually 50 ohms. You can try this out by measuring a
470 ohm reisitor or a 22 ohm resistor both with the MFJ259 alone and them
through the filter. Very different readings.

The MFJ 731 does a much better job. Mine was tuned to 1620 and works well at
around 100 ohms up to 28 mHz and with 22 ohms up to 7 mHz.

Try it for using in proximity to a BC station. I have no connection to MFJ.

73  Don K5AQ


--
FAQ on WWW:               http://www.contesting.com/FAQ/towertalk
Submissions:              towertalk@contesting.com
Administrative requests:  towertalk-REQUEST@contesting.com
Problems:                 owner-towertalk@contesting.com