What Jon describes confirms in detail what I stated in my earlier mail: it
all depends whether or not the TX antenna remains RESIONANT during
reception. So in most cases (depending on the feed system), this willd
epend on the length of the feed line and the termination of the feed line
(open, short). Makes 100% sense, Jon.
What Jon also says is that when the band was very quiet, he realluy
listened on the vertical (better Signal strength). John, what you should
try is to use an MFJ noise silenvcer, and use the TX antenna as noise
source. You will be able to toally tune out the noise from the antenna. It
proves that this is NOT noise coming from "everywhere" (there would be no
specific or constant phase to it), but coming from a very specific closeby
source: your vertical.
73
John, ON4UN
At 18:54 3/5/98 -0500, you wrote:
>At a former QTH, I had a 113-ft shunt-fed tower, with a couple of yagis for
>top loading. I had over 200 slightly-buried radials, filling a rectangle
>approximately 270-ft by 140 ft, with the tower in the center.
>
>I had a short (185-ft) European Beverage that crossed within 50 feet of the
>tower, 10-ft. high. I had a 600-ft. East and West wire (unidirectional,
>switched at
>each end) that ran over the edge of the radial field, about 70 feet from the
>tower.
>
>There was never any noticable noise pickup from the tower on the East and
>West Beverage. This as compared with three Beverages I had 1/2 mile away in
>the woods.
>
>The short European Beverage near the tower, however, had some interesting
>coupling
>to the tower. It wasn't by design, but it just happened to work out that the
>feedline (75 ohm hardline) was about 1/2 wave electrical length. When I
>switched the antenna switch so the vertical was in-line (hooked to the amp
pi-
>net), signals on the short Beverage always INCREASED in strength. I assume
>this was because signals being picked up on the vertical were being
>coupled
>to the Beverage. In times of local storm activity, however, the NOISE
coupled
>from the tower to the short Beverage was stronger than the enhanced signals,
>and I would copy signals better with the tower switched out-of-line. (At all
>times cited I was receiving on the short Beverage, not the tower itself. I
>seldom found signals better on the tower than on the short Beverage near it).
>
>Signals were better copy on the 500-ft Beverage 1/2 mile out in the woods
>about 80 percent of the time.
>
>73/Jon AA1K
>---------------------------------------------------------------------------
---
>REPLY FROM: Zaimes, Jon
>Having read all messages which started with KZ5MM's noisy Beverage, it
>appears that the proximity (noise) problem (Beverage near Tx vertical)
>exists when the Tx vertical has elevated radials. Conversely, a Beverage
>seems to co-exist okay with a nearby vertical which uses non-elevated
>radials.
>
>The N4KG feed method is interesting. I notice that if you remove all but
>one of the radials, it looks suspiciously like a half-sloper :-)
>
>73, de Earl, K6SE
>
>
>_____________________________________________________________________
>You don't need to buy Internet access to use free Internet e-mail.
>Get completely free e-mail from Juno at http://www.juno.com
>Or call Juno at (800) 654-JUNO [654-5866]
>
>
>--
>FAQ on WWW: http://www.contesting.com/topband.html
>Submissions: topband@contesting.com
>Administrative requests: topband-REQUEST@contesting.com
>Problems: owner-topband@contesting.com
>
>--
>FAQ on WWW: http://www.contesting.com/topband.html
>Submissions: topband@contesting.com
>Administrative requests: topband-REQUEST@contesting.com
>Problems: owner-topband@contesting.com
>
>
***************************************************************
* John Devoldere, ON4UN, AA4OI, OT8T *
* e-mail: john.devoldere@innet.be *
* address: Poelstraat 215 *
* B9820 Merelbele *
* Belgium *
* mailing addres: P.O.Box 41 *
* B9000 Gent, *
* Belgium *
***************************************************************
* *
* PLEASE CALL US IN THE CONTESTS (ON4UN OR OT8T). THANK YOU! *
* *
***************************************************************
--
FAQ on WWW: http://www.contesting.com/topband.html
Submissions: topband@contesting.com
Administrative requests: topband-REQUEST@contesting.com
Problems: owner-topband@contesting.com
|