That's an important question, Jim.
A receive preamp is one of my favorite topics and one of the top 10
questions I'm asked by hams, regardless of whether it is for low band RX
antennas or in the VHF and above region. The question is "Do I need a
preamp?" to which I always respond "I don't know, do you?". Its not meant to
be a snooty response but a valiant effort to get the person to study and
learn about preamps and what one does in an antenna system or circuit. The
person can then determine why they do, or do not, need one and assess what
is right for their situation. The one wavelength Beverages used at my
station have sufficient gain, and adequate SNR that I don't believe one is
necessary.
As I noted in the paper, geographical areas differ and there are RX antenna
designs that benefit from a preamp, but not all of them in all situations.
73 Joel W5ZN
-----Original Message-----
From: Topband <topband-bounces+w5znjoel=gmail.com@contesting.com> On Behalf
Of Jim Brown
Sent: Tuesday, January 14, 2025 2:58 PM
To: topband@contesting.com
Subject: Re: Topband: Comparison of Vertical Arrays for Low Band Receiving
On 1/14/2025 12:13 PM, w5znjoel@gmail.com wrote:
> Thanks. No, I did not have preamps at the feed point of the Beverages.
Is the sensitivity of a one wavelength Beverage low enough that a preamp at
the feedpoint is needed? Loss in decent coax is pretty low at 2 MHz, and
where I live, electronic noise has gotten high enough that I can't imagine
it being a limitation. My reversible one wavelength Beverages (one EU-VK,
the other SA-JA) point to noisy homes facing EU and JA, so they've become
next to useless.
My 8 acres are in a dense redwood forest, with terrain that varies by at
least 50 ft in elevation, so any of these vertical arrays are out of the
question. I am finding some benefit from an array of two VE3DO loops spaced
5/8 wave, but one of them is quite close to the noisy EU home, and points at
it. :) I'm phasing it with an NCC-1, which allows me to shift the pattern
between northern EU and New England.
73, Jim K9YC
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