Topband: Vertical SWR problem

[Roger D Johnson]

>>I've just installed a Titanex V160S vertical (87') with a V160AS (160m
>>only) tuning unit. Yesterday I connected 12 radials (130') each, adjusted
>>the taps on the tuning unit coil with an MFJ SWR analyzer, and got the
>>resonant point down to about 1850 khz. with tolerable SWR (less than
>>1.5:1) at 1805 khz. So, here's the problem: today I added another 16
>>radials, and the resonant point moved up to 1900 khz. The SWR is now high
>>enough at 1825 khz that the amp shuts down. I tried adjusting the taps on
>>the coil in the tuning unit, but to no avail.
> 
> 
>>Anyone have any suggestions as to how to get the resonant point to a lower
>>point in the band? Thanks.
> 
> 
>>73, Jim   W1YY/7

Hi JIm..

The MFJ (and others) has a well known tendency to give wacky
readings when broadcast band signals get into it. This often
happens when trying to tune nice, big 160m verticals! The added
radials should not have had a large effect on the resonant frequency 
which leads me to the conclusion that something else is going on.
There are high pass filters available to help with this problem.

73, Roger
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