Buy the RG-6 it comes in Quad Braid if that's what you like but you need to
get it in the direct bury because its filled with suff critters don't like.
And will reseal its self if they chew it.
N9IWW
Kevin Adam
1239 W. Till Road
Fort Wayne, Indiana 46825-2145
Mobile (260) 704-4080
-----Original Message-----
From: topband-bounces@contesting.com [mailto:topband-bounces@contesting.com]
On Behalf Of Tom Rauch
Sent: Thursday, March 04, 2004 7:19 AM
To: David J Rodman MD; topband@contesting.com
Subject: Re: Topband: Beverage feedline suggestion
> beverage coax switch and another 200' to the station. If the antenna is
> to be used on 160 and 80m, what feedline is suggested to maximize signal
> and minimize cost. Right now the antenna is fed with "mini" RG59 and
I'm not sure what "mini" RG-59 is. I assume it is standard CATV RG-59-type
cable that is called F-59?
Assuming you have a reasonable NF in the receiver preamplifier system, good
low-resistance connections on the shield at every joint, and isolate the
shield from the Beverage ground... S/N ratio won't change much with length.
ALL of my antennas have preamps in the house. The most distant antennas have
three hundred feet of F6 ("RG-6") to a switching system, and then over 2500
feet of F11 (RG11 style) cable to the house.
> the antenna is at least 1 S unit less noise than my other two antennas.
> I presume the quietness is loss of signal from the feed line length.
I'm not sure what an S unit is on your receiver. On some of my receivers an
S unit is actually one dB near S-1. On some an S unit is about 2-3dB at
mid-scale. It is NEVER six dB on anything I normally use. An S-unit might
not be very much difference at all!! It almost certainly is not anywhere
near six dB except perhaps up near S-9 on some receivers.
The reduced noise could partly be because of direction and feedline loss.
> haven't matched the antenna to the feed transformer yet, but it is hard
> to imagine that would be 6-10dB loss.
A 6:1 SWR from a source to a load results in 3dB mismatch loss. Without
matching the antenna to the feeder there is 3dB lost energy transfer, which
(3dB) is typically about an S unit on most meters near mid- or low- scale
end of most S meters. The feedline loss should be a similar value, but you
need to consider the DIFFERENCE between the feedline for the NE antenna and
the other antennas. If your other antennas are MATCHED to the feedline with
perfect lossless match and have zero loss feedlines compared to several
hundred feet of F-59 cable, there only would be six dB difference.
Your 6-10dB loss estimate is probably actually 2-4dB loss, which on most S
meters would show as just over one S unit on the lower portion of the scale.
73 Tom
_______________________________________________
Topband mailing list
Topband@contesting.com
http://lists.contesting.com/mailman/listinfo/topband
_______________________________________________
Topband mailing list
Topband@contesting.com
http://lists.contesting.com/mailman/listinfo/topband
|