Topband: Antenna Measuring Oddities

Eric Rosenberg wd3q at
Thu Feb 8 00:51:10 EST 2007

I recently add an 80m inv-L adjacent to my 160 inv-L, sharing the 
radials but having a separate feedline. It's 55 ft up in the tree, with 
the horizontal ("tail") 25 ft, running south.

I measured the SWR with a MFJ-259B and then ran 100w through the antenna 
and measured it with my RF Applications VFD meter. The results were very 

I live in a hight RF environment (I'm ~5 miles from a broadcaster 
putting out 50kw on 1500 kHz.  I've heard that the MFJ unit has problems 
in the high RF environment, so my instinct would be to favor the VFD 

Freq   MFJ 259B        RF Apps. VFD
3400    4.2
3500    2.6             1.6
3550                    1.4
3600    2.5             1.3
3650                    1.3
3700    3.0             1.4
3750                    1.6
3800    4.1             1.8
3850                    2.0
3900    5.2             2.2
3950                    2.4

I'm not sure how to reconcile or really believe either one!

Any thoughts  or suggestions are appreciated

73 and thanks,
Eric W3DQ
Washington, DC

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