Topband: Ant Analyzer Assistance request -- funky readings

K4SAV RadioIR at charter.net
Thu Jan 24 17:23:45 EST 2008


Rick Hiller wrote:

>Hello,
>
> 
>
>I was helping a friend put his ‘postage stamp lot --low to the ground’  80
>meter loop on 160.  So, we opened the loop to cause a ½ wl 160 antenna
>folded into a polygon.
>
> 
>
>Placing the MFJ-269 analyzer at the loop (open or closed) feed point shows
>fairly appropriate readings at 3.600 (R 98 +J25) , but anything outside this
>range down thru 1.8Megs and below, or up toward 7Megs shows continuous R
>values of ZERO with a varying j value.  Measurements were taken right at the
>feedpoint, which is 45 degrees off center (approx).
>
> 
>
>My concern is the ZERO R value -- for even occurring, but also that it
>occurs over such a very wide range of frequencies ..............
>
>
>  
>

The same reading on 3.6 MHz with the loop open or closed really threw me 
for a moment until I realized that this is an off-center-fed open loop. 
So about 30 feet high should get you into the low teens for R on 160, 
including resistance loss. That should be readable on the MFJ although 
it's not much meter movement. The MFJ could be a little out of 
calibration on the very low end, or more likely it is getting just 
enough broadcast station RF to mess up the reading.

Jerry, K4SAV


More information about the Topband mailing list