The object is to establish a stable RF ground and not necessarily a very low
ohmic one. Drive three 4-8' rods (use a rented rotary hammer drill) will do
for starters with say 3 20-30' radials at each one. Radials can be under the
Beverage 20' or so from the termination, double back on themselves or any
convenient path. I use cheap hamfest #20-22 insulated hookup wire just
laying on leaves and pine needles.
My granite hilltop with only 4-24" of soil cover measures 200 Ohms with 3
4' rods driven at an angle and 3 20-30' radials each, at both ends. The far
end of one also terminates at a point that I cant use any in-front radials
so one is at the termination, another to one side (a stone wall is at the
other side) and the last is back under the antenna about 10'.
The transformer designs for a 2 wire reversible or single wire will have to
be designed to subtract the RF ground loss. This is easiest with a
MFJ-259/269 and a single wire at first with a carbon pot termination. The
transmission line mode impedance doesnt change. So for my 4 700-900'
reversibles Im using 270 Ohms for the ground dependent windings and either
175 or 93 Ohms for the transmission line calculations. Using the very high
8500 Al BN73-202 binocular cores it is not possible usually to get a
precise match when only 4-6 turns are involved and contrary to the ON4UN
description you can wind at odd turns also; ie.a 5T winding can be center
tapped on turn # 2 1/2 which will be at the other end of the core....its
still balanced. Ive found F/B to exceed 20dB most of the time and be better
or worse sometimes. I use an external switchable attenuator to calibrate the
TS-950SD S meter so the results are accurate enough for this project.
----- Original Message -----
From: "Thomas" <email@example.com>
Sent: Sunday, January 23, 2011 8:46 AM
Subject: Topband: Beverage ground rod substitute
> All of this talk about a short Beverage antenna has me thinking I just
> might be able to install one 250-280' E-W wire. One issue would be the
> ground rod. The earth here is Caliche which is quite similar in
> properties to concrete, so I can't drive a ground rod into it. I've
> thought about using short buried radials like I do with my K9AY, but the
> Beverage termination points will be in the extreme corners of my lot.
> Any ideas what could be substituted and might work as well as the simple
> ground rod earth? It is funny I find myself attempting to make the
> proverbial silk purse from the sow's ear!
> Tnx, Thomas - AC7A (Tucson)
> UR RST IS ... ... ..9 QSB QSB - hw? BK
UR RST IS ... ... ..9 QSB QSB - hw? BK