Congratulations Joel on a very fine paper on RX antennas and sharing you hard
work.
I enjoyed the read and the exceptional depth of your work. Matter of fact I
have read it 3 times now!
Lee K7TJR OR
-----Original Message-----
From: Topband <topband-bounces+lee=k7tjr.com@contesting.com> On Behalf Of
w5znjoel@gmail.com
Sent: Tuesday, January 14, 2025 2:18 PM
To: jim@audiosystemsgroup.com; topband@contesting.com
Subject: Re: Topband: Comparison of Vertical Arrays for Low Band Receiving
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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