Topband: Antenna analysers in close proximity to BC station.

[Bob K6UJ]

Tom,

I will be interested  to see what the solution(s) will be  for the BC station interference.

Wanted to thank for the reference to the impedance problem calculators.  They are great!  

73,
Bob
K6UJ


On Nov 2, 2012, at 2:21 PM, Tom Boucher wrote:

> 
> 
> A ham friend asked me to design a matching network for his 160 metre end fed quarter wave, so I asked him to provide an impedance reading using his MFJ-259B. I would then use the Berkley site (http://bwrc.eecs.berkeley.edu/Research/RF/projects/60GHz/matching/ImpMatch.html ) to provide the necessary values for an 'L' network, as I have done many times at my own station.
> 
> 
> 
> The readings he provided were total nonsense and quite erratic, so we concluded his MFJ-259B was dead. He assured me that he always does a static discharge before connecting the MFJ.
> 
> 
> 
> So I paid him a visit, taking along my Palstar Antenna analyser thing, which has always performed well at home, and what-do-you-know, the readings on that were also erratic, total nonsense and it behaved in a way I have never seen before. 
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> 
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> Than someone suggested the problem may be due to a 50Kw BC station on 909 KHz, situated less than 5 miles away, causing both antenna analysers to misbehave.
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> 
> We ended up with a good old-fashioned link coupled parallel tuned circuit with the antenna tapped a few turns up from the ground end. This works fine but he is power limited due to arcing across the tuning capacitor. So we would ideally like to revert to the 'L' network plan, but how to use the antenna analyser in the presence of a high BC station field. Anyone any ideas?
> 
> 
> 
> 73
> 
> Tom G3OLB
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