Topband: Bev wire under a path?

[John G3PQA]

Bud is right for a single wire beverage, where matching is not important, 
but dont expect to have a good f/back ratio with a 2-wire. However the 
gravel will help a little as it is non conductive, but the 15ft length of 
wire on the ground will cause a big Z discontinuity with unknown effects on 
the matching which of course adversely affects the reflection xfmr and 
terminations.
You are getting good f/back on your bev at present, shame to spoil it 
(except the EZNEC analysis showed loops to work at least as well, or 
better).

I ran a WD1 beverage for 30ft at 20ft high over a stream and it was 
terrible.
I use a duct myself for the same reasons as Bud because my NE/SW beverages 
cross the footpath buried for 8ft just under surface, wire in water pipe, 
but it is not a tricky 2-way bev.
Do try it by all means, it will be interesting to see what happens, but if 
worse, surely you can get some wooden posts or something each side of the 
road which are better than a thin pole.
73
John.

----- Original Message ----- 
From: "W2RU - Bud Hippisley" <W2RU at frontiernet.net>
To: "Neil G0JHC" <g0jhc at blueyonder.co.uk>
Cc: <topband at contesting.com>
Sent: Friday, January 06, 2012 2:05 PM
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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UR RST IS ... ... ..9 QSB QSB - hw? BK