Two unrelated questions:
A recent improvement to my station has brought other issues to the
forefront. I am going to need a serious filter to keep AM BC
stations out of my preamp. I had been thinking bandpass filters, but
none I am aware of roll off quickly enough below 1.8 MHz. I am now
investigating high pass filters. The W3NQN filters sold by Array
Solutions look very impressive. Is there anything else (maybe a
little cheaper) anywhere near this or are these in a class by
themselves? This will be a receive only application.
I am also looking for a better formula for calculating inductance of
single layer air core coils. Although I have done well enough over
the years with the "simplified formula" from ARRL Handbooks which
gives a "close approximation" I now wish for something better.
Ideally I would like something accurate for coils of any length to
diameter ratio, including very short coils. A free downloadable or
online calculator would be great, but a plain old formula is fine
too. I have found several on the internet but which ones to trust?
Any guidance would be appreciated.
Thanks, 73, & HNY!
Paul N1BUG
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UR RST IS ... ... ..9 QSB QSB - hw? BK
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