Hi Mike,
Sorry, I somehow missed your January 14 email below. I do have a preamp
available at the shack end but rarely use it. It is built into the RAS-8. I
don’t know what device Gary used in the design but it does have high pass and
low pass filtering.
As I noted on page 13 of my paper, I did try some preamplification in the shack
to “equalize’ the noise floor of the Beverage and YCCC-9 to that of the BSEF-8
and HiZ-8. Even though the noise floor did increase I could never document an
increase in S/N or forward signal above the noise floor so I didn’t use the
preamp when recording the data.
I don’t want to suggest this is a summary dismissal to using a preamp for a
Beverage as there may be times when it could be beneficial, as you note below.
I believe we all agree every person’s installation will vary and a preamp may
add some benefit, but adding one just because a person “thinks” they need one
isn’t a valid reason!! 😊
73 Joel W5ZN
From: Mike Waters <mikewate@gmail.com>
Sent: Wednesday, January 22, 2025 3:16 PM
To: Jim Brown <jim@audiosystemsgroup.com>; w5znjoel@gmail.com
Cc: topband <topband@contesting.com>
Subject: Re: Topband: Comparison of Vertical Arrays for Low Band Receiving
Gentlemen,
I never used preamps at the feedpoints of my Beverages*, and I probably should
have left out "at the feedpoint". I just noticed that Joel's graphs sometimes
showed a very low signal level from the Beverages, and was curious.
*However, I did use a preamp at the station end of the F-6 feedlines to them.
(A series 2k pot there adjusted the level to match the TX antenna; and on
occasion eliminated intermod.) The output of a Beverage is rather low, and
sometimes I would switch between them and the inverted-L, etc.
Having said that, somewhere I read that on occasion, others absolutely needed
them at the feedpoint, when the noise floor was exceptionally low (I believe
just before sunrise). But I guess that's a moot point here.
The longest F-6 feedline here was about 600'.
On Tue, Jan 14, 2025, 3:10 PM Jim Brown <jim@audiosystemsgroup.com
<mailto:jim@audiosystemsgroup.com> > wrote:
On 1/14/2025 12:13 PM, w5znjoel@gmail.com <mailto:w5znjoel@gmail.com> wrote:
> Thanks. No, I did not have preamps at the feed point of the Beverages.
How about at the station end, Joel? Sorry, I should have been more clear.
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, ...
As I said, sometimes it is, according to others. Sorry I don't have a
reference. :-)
73 Mike
W0BTU
https://web.archive.org/web/20190827040547/http://w0btu.com/
<https://web.archive.org/web/20190827040547/http:/w0btu.com/>
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