[Lowfer] LOWFER Receivers and Antennas

[Douglas D. Williams]

Hi Ben. I use two receivers for LF work. The first is an R75 with TCXO and
dual 250 Hz CW filters, coupled with a modified (with OCXO for stability)
Amrad upconverter. The second is a Winradio G33DDC (Excalibur Pro) SDR.
Both are fed with the same antenna, a Clifton Labs active whip which is run
through a 500 kHz LPF and a splitter so that both receivers can use the
same antenna. Like Pat Bunn, I use common mode chokes to cut down the crud
that can make it's way out to the remote active whip via the coax shield.

Basically, to be successful at receiving the ultra narrow band modes that
are being experimented with by Part 5 licensees, Part 15 Lowfers, and the
guys across the pond, you need a receiver that is (1) sensitive at LF, (2)
has very good frequency stability (by "very good" I mean TCXOs, OCXOs, or,
best, GPS disciplined), and (3) you need to be able to tell exactly what
frequency you are receiving, at least within 1 Hz.

I had a fellow remark just the other day that my reception report was 1 Hz
off. :-)

You biggest enemy will likely be local noise generated in your and your
neighbor's houses. This is why most of us locate our antennas away from our
houses, in the quietest spot we can find on our property. JD even makes
field trips out to some farmland he owns.

Much of the time, the signals we are reporting on are inaudible via
conventional CW.

Good luck!

-Doug KB4OER






On Sun, Oct 6, 2013 at 9:44 AM, Ben Hall <kd5byb at kd5byb.net> wrote:

> Good morning all,
>
> I've been in lurk mode here for many months.  I had not seen the topic of
> receivers come up - if it did, I sure missed it!  I have seen some
> discussion on antennas from time to time.
>
> I'm curious to what people are using as a LOWFER receiver and antenna.
>
> I have small collection of receivers here - a Navy RBL-3, a Navy RBA, a
> Rycom Selective Level Meter (6040 I think?), plus have used the Jackson
> Harbor LF up-converter with my Elecraft KX3 and even one of those USB
> dongles with both the 4 MHz up-converter and a 125 MHz up-converter.
>
> For antennas, I've been using a slightly-modified PA0RDT mini-whip, and
> have a N7ZWY active short monopole ready for testing as soon as the
> thunderstorms move out of the area.
>
> thanks much and 73,
> ben, kd5byb
>
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