Hi topbanders,
Can someone give me more information about the tunable filter designed =
and sold by MFJ to suppress the bad influence of AM-BC on mediumwave =
when measuring with 160m antenna's !
Here in Europe I have never heard anyone using such a filter, although =
it is mentioned in ON4UN;s book...
- What is the product name of this filter ?
- Is it acutally available by MFJ ?
- How does it perform - anyone who has seriosly tested it ?
- How does it work - any schematics ?
- Why does it NOT completely offset the R and X values of the ant- =
itself - to my understanding ANY filter between the analyser and the ant =
feedpoint will change the displayed Z of the antenna.... am I wrong ?! =
Maybe I don't yet understand what that "filter" actually is...
Please let me know about - it would be extremly useful when making ant =
measurements at our contest site PI4COM - here we have a 20kW AM =
broadcaster roughly 1kM from our large verticals.... any measurement =
between 7Mhz (!) and 1.8Mhz are completly useless as you will see the AM =
program moving the needles of the instruments... yes, even during the =
day on 40m measurements are nonsense, as the needle is moved by the =
broadcast stations of the European 41m BC band.... (we use 3 ele yagi) =
the BC's >59+60dB also at noontime...
Any idea for measurements ?!
Ulli, PA5AT
low-band OP at PI4COM
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