For correct performance I would suggest enough to cover that band in
half octaves. The filters get narrower and more difficult to build as
you get lower in order to achieve this if you insist on passive filters
(including almost certain higher insertion loss). It is the only way to
approach this seriously. Once you get low enough where the RF is "high
speed audio", I don't know why we don't consider active filters as much
easier and preferable. We are not really dealing with large signals
down there and adequate filtering and sensitivity seem to me to be more
important than huge IP3.
Remember, these are thoughts, not directives. I am muttering out loud.
Bob
N4HY
Chris seeber wrote:
Harry,
You need some kind of external low pass / band pass filter. If you get
them, it works great with the filters installed in the 5000's RX in /
out loop. I purchased a low pass filter from W1VLF that works really
well. But to cover the entire band, you would probably need two or
three of them. Good Luck.
73
Chris, KA1GEU
-----Original Message-----
Message: 12
Date: Sun, 25 Jan 2009 09:40:36 -0600
From: Harry Williams <willisw...@msn.com>
Subject: [Flexradio] Longwave Reception with Flex 5000
To: <flexradio@flex-radio.biz>
Message-ID: <col117-w80c680f776e6cb7756336884...@phx.gbl>
Content-Type: text/plain; charset="iso-8859-1"
Hi,
I am wondering if any of you have attempted to use the Flex 5000 to
receive longwave stations below 500KHZ. I have listened down in that
range and the only thing I hear is BCI from the stations in the US
broadcast band. I assume a filter is needed to reject the BC band
interference.
73,
Harry
W0LS
------------------------------
--
ARRL SDR Working Group Chair
Member: ARRL, AMSAT, AMSAT-DL, TAPR, Packrats,
NJQRP, QRP ARCI, QCWA, FRC.
"It is human nature to think wisely and act in
an absurd fashion.", Anatole France.
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