"Pierre Vachon" wrote
Hi there, I am trying to build a longwire antenna for use in the 20 meter
band to 70 meter band area. I was looking for advice on what materials to
use for the antenna and the lead in lines. I will hook it up to a Drake
r8B
radio. What is the minimum height it has to be? Where to ground it?.
Actually, does it have to be grounded if the radio is grounded at the
outlet?

I am a little limited in space as my yard is only 75 feet long and there
are
power lines at the front. I assume that they are the source of an
irritating
hum on the receiver on certain frequencies.

Thanks for the help in advance.

Pierre

The minimum height above ground is about 1 millimeter ;-) That's where
Hurricane Isabel dumped one of my long wires last fall. It took over a week
to clear debris away before I could get it back up in the tree it was pulled
out of. It still received quite well in the meantime, even laying on the
ground. Of course the higher the antenna, the better it receives. At an
angle of more than 45 degrees, there is very little effect on the direction
the sloping wire points. At an angle of more than about 75 degrees, you are
approaching a "vertical" which is known for it's higher background noise.
Not desirable in DX work.

You didn't say if you are going to use a Balun transformer at the antenna
and coax feedline to connect to the radio. *If* you do, then you can
certainly ground the shield of the coax at the balun (even ground the unused
side of the balun), and shield ground the coax again before it comes into
your home. That can certainly help reduce noise. If the coax shield is not
grounded, the home electrical ground can "feed" noise from the radio, out
the coax shield, and back into the coax center conductor at the antenna
connection. Shield grounding does prevent this from happening. It is also
required in order for any static or lightning protection device to work
properly, should you use those devices.

Good luck,

Jack