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[TowerTalk] RE: [CQ-Contest] Testing Stubs

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Subject: [TowerTalk] RE: [CQ-Contest] Testing Stubs
From: (
Date: Tue Aug 5 12:48:54 2003
you are seeing what i would expect if there were:
1. a source of harmonics after the stubs, on the tower, near the tower, etc.  
2. a leak between the radio and stub that radiates the harmonic before the 
stub can do its job.
3. overload in your receiver thats generating the harmonic there.

while the stubs are probably working ok the other routes overwhelm the 
radio/amp generated harmonics that are properly suppressed.  ground rods are 
probably not involved.  grounding of equipment cases, good coax with properly 
installed connectors, and in some cases fixing leaks caused by bad cases on 
radios, amps, swr meters, antenna tuners, antenna switches, etc is necessary.

> Gee, I'm not alone in receiving less-than-stellar performance from stubs.  I
> have made several sets of stubs using various methods of tuning them and
> they just don't work at my QTH.  But I took one of my stubs to a friends QTH
> and he was able to show me that my stub did indeed give 20 dB of suppression
> on the second harmonic - just like it is supposed to.  And he loaned me one
> that he had made and used successfully at his location and it doesn't work
> for me either.  I run monobanders and 4 square phased arrays and he runs a
> TH-11 and verticals.  He does 16 ground rods arranged around his back yard
> (in the city) whereas I only have 2 ground rods and I am in a rural area.
> And we have used these same stubs on DXpeditions with good results.
> It could be that there is such a thing as a 'hanging tree' for stubs.
> de Paul, W8AEF

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