Mike:
1. Maybe the type of rocky ground is the reason.
2. Take down all the other wires and check the L (or T) by itself, still
using switchbox.
3. Take out the switchbox and just feed the antenna directly (still by
itself, no other wires)
4. If things are still bad then the problem probably has something to do
with your location.
------------------ Wes Attaway (N5WA) ------------------
1138 Waters Edge Circle - Shreveport, LA 71106
318-797-4972 (office) - 318-393-3289 (cell)
Computer Consulting and Forensics
-------------- EnCase Certified Examiner ---------------
-----Original Message-----
From: topband-bounces@contesting.com [mailto:topband-bounces@contesting.com]
On Behalf Of Mike & Coreen Smith
Sent: Saturday, November 07, 2009 6:44 AM
To: topband@contesting.com
Subject: Topband: Low Alpha Delta DX-A twin sloper BEST antenna here -
howcan that be?
Sorry for the long and rambling post. . . .
OK gang, I know antennas "fairly" well, but this has me stumped...really
REALLY stumped. I've beat myself up over this for 2 yrs. straight. I just
can't get it. I am (almost) ready to rip everything down and start from
scratch)
I posed a ~similar~ question last year and have tried some different things,
but I'm losing my patience with the wire here (hi)
BACKGROUND:
At my old QTH, I ran an inverted L...5/16thWL and fed with a 800pF cap in
series. A dozen to two dozen 1/4wl radials(depending on how many got broken
in the summer)over soggy ground. It meandered up 50-ish or so feet with the
remaining 117' up/down/over/under trees --even the tip sloped back towards
the ground 20' or more.....and it ROCKED....I mean, I wasn't any VE1ZZ or
anything but I felt I was upper middle crust of the W1/VE1 pileup. I also
had the exact same tower and exact same Alpha Delta DX-A twin sloper up (for
reference) and it s*cked...really bad. Easily several S units below
anything else on 40-80-160m
NOWADAYS:
Fast forward to new QTH...same 48' DElhi self supporting tower set in
concrete....same 2 long 6m yagis on tower (48/64')....same lil' sloper
mounted @ 24' off side of tower....
I have tried 2 iterations of a plain inverted L.....currently it's a "T"
antenna. Sloping 55' or so up and 2 T's @ 55' or so each sloping @ aprox 45º
to the ground....loads nicely with a few uH @ the base. Seems quieter than
the A-D twin.
I have tried shunt -and- series feeding my 48' tower (no problem to do).
They have all loaded well and I got a good SWR match with a usually narrow
window 50Kcs maybe of 2.1:1 SWR of which to operate in. I have 25 or so
1/8wl to 1/4wl radials - 1" below the grass. Ground is rocky shale? sort of
stuff. My QTH is on a nice high ridge and I do quite well on VHF and other
HF bands.
My signal is pitiful on **all** the 160m antennas I've tried....with the
exception of the 1/4WL Dx-A twin sloper @ 24' !!! (it's best but it barely
works)
The little/low twin sloper off the side of the towe is ALWAYS the loudest on
the band....by usually 6dB or more........I know this can't be right.
How can this be? I am using a 4-1 antenna switchbox (Ameritron I think) @
the base of the tower which the antennas all share. Many years back I
modified it so all antennas "floated" (instead of being grounded) when not
selected as I was using this as a K8UR sloper system switchbox at one time.
I am pretty sure (but not 100%) that I even ran a separate chunk of coax
right out to an inverted L last fall in desperation. I do lots of antenna
experimenting, so it's sometimes hard to remember the 45th iteration of a
trial I had a couple years ago, hi.
I *DO* notice significant SWR curve changes on the lil' wee sloper if I make
any mods to any of the other "REAL" 160m antennas.
I either have interactions in the switchbox, or proximity between antennas
or something that I am totally missing. All 160m antennas are quite close
(less than 20-30' away).
Logic tells me there is no way in heck the very low Alpha-Delta DX-A twin
sloper can __always__ be the best antenna to transmit and receive on. YET
is is !!? From what I see on the cluster, web and hear on the air, I can
hear quite well, but DX stations normally have to be 559-579 before I even
get a QRZ.....I am currently running ~750W.........
I'm cracking up.....too much listening to QRN.......sorry for the long post.
Thanks for any insight. I am ready to put a Webster Bandspanner on my
mobile and go sit out in the yard and DX.
<hi>
VE9AA Mike
Mike, Coreen & Corey Smith
699 Rte 616 Keswick Ridge
NB
Canada
E6L 1T1
_______________________________________________
160 meters is a serious band, it should be treated with respect. - TF4M
_______________________________________________
160 meters is a serious band, it should be treated with respect. - TF4M
|