Several years ago, I measured a half dozen or so bandpass filter sets
that I was able to borrow for NCCC members, and some that I owned. I
wrote up a report, that was published in the National Contest Journal
and the NCCC newsletter, "The Jug." That report, with links to the
actual data for each filter on each band, is on my website.
http://k9yc.com/BandpassFilterSurvey.pdf The filter sets I tested were
ICE, Dunestar, W3NQN sold by Array Solutions, and the very nice TXBPF
set designed by Bob Henderson, 5B4AGN, based on a W3NQN design, and for
which Bob did several group purchases. In addition, Bob sent me data
that he measured on 4O3A filters rated for use on power amp outputs, and
that data is in the report.
73, Jim K9YC
On Tue,9/13/2016 1:17 AM, shristov wrote:
"rick@dj0ip.de" <Rick@DJ0IP.de> wrote:
However the Dunestar SPECS on their web site claim 40dB band-to-band
rejection. I was just quoting the specs.
http://www.dunestar.com/store/Single-Band-Bandpass-Filters-pid-4.html
Hi Rick,
that's what I had in mind.
Taking the 7 MHz filter as an example,
there is 40 dB attenuation on ~3.5 MHz.
But on 6 MHz the attenuation is practically nil.
Your preselector is the right tool for the job.
But it's receive-only, given the 7.5 dB passband attenuation.
Dunestar etc filters must have a much wider passband
in order to achieve low enough passband attenuation,
making them suitable for transmitting.
Best 73,
Sinisa YT1NT, VE3EA
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