You could also shorten the Beverage length with loading coil(s) and run coax
under the gravel if thats a possible option.
Since the coils slow down the wave a bit you have to factor in the velocity
factor so the electrical length doesnt flip the directivity at around a .5
VF. Using Slinkys for a continuously loaded element Ive reduced a well
performing Beverage to 175' which calculates to a .59 VF. Its 5 of the 3"
diameter Slinkys in series and a 1200 Ohm resistor for my granite ground.
Carl
KM1H
----- Original Message -----
From: "W2RU - Bud Hippisley" <W2RU@frontiernet.net>
To: "Neil G0JHC" <g0jhc@blueyonder.co.uk>
Cc: <topband@contesting.com>
Sent: Friday, January 06, 2012 9:05 AM
Subject: Re: Topband: Bev wire under a path?
My Northwest Beverage does exactly what you are proposing. It crosses a
shared gravel driveway that leads to my home. Fortunately, there are small
trees on each side of the driveway (in fact, they hold up segments of the
Beverage), so I simply ran my Beverage wire down one tree, across the
driveway in a trench a few inches deep, and back up the tree on the other
side.
I recommend strongly — especially if the ground ever freezes at your QTH —
that you put the underground portion of the Beverage wire in a length of PVC
tubing and leave a little slack in that portion of the wire. Along with
some of our neighbours on this same driveway, we learned the hard way a few
years ago that even direct burial power lines *break* due to the repeated
stresses caused by vehicular traffic and frost heaves in the area of the
wires if some form of rigid conduit isn't used.
And the farther down you can place the wire, the less likely it is to
gradually work its way back up to the surface over time.
I'm sure there's some signal loss and impedance bumps caused by the earth's
proximity, but it's still a whole lot better than not being able to have a
NW Beverage at all!
Bud, W2RU
On Jan 6, 2012, at 8:23 AM, Neil G0JHC wrote:
> I currently have a 585ft Bev, which at around 200ft has to pass over
> a
> gravel track which is 12-15ft wide. I am contemplating...burying the wire
> 2 or 3 "
> under the gravel track. I am using WD1-a wire.
>
> Has anyone any experience of the effect on performance. I will be burying
> approx. 2-3% of its total length.
> Neil G0JHC
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