Topband: Comparison of Vertical Arrays for Low Band Receiving

[w5znjoel at gmail.com]

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 at gmail.com> 
Sent: Wednesday, January 22, 2025 3:16 PM
To: Jim Brown <jim at audiosystemsgroup.com>; w5znjoel at gmail.com
Cc: topband <topband at 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 at audiosystemsgroup.com <mailto:jim at audiosystemsgroup.com> > wrote:

On 1/14/2025 12:13 PM, w5znjoel at gmail.com <mailto:w5znjoel at 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/>