At 07:05 12/10/1998 PDT, Roger VE3ZI wrote:
>
>I have just put up a couple of short (500') beverages as being all I can
>reasonably do before the snow flies. They seem to work well (quite
>beautifully on A35ZL!), but both pass under telephone/low voltage power
>(but not cable TV) lines. I find that I am getting quite a number of
>'sproggs' across the band, including a loud drifting unstable carrier.
These are probably being generated in the neighbourhood, arriving through
power line conduction, and magnetically coupled into the beverage. There is
no way to shield a beverage from a local magnetic field. Furthermore, its
low output level makes it all the more susceptible to interference like this.
You could try to suppress the interference at the source/s (good luck), or
else try a different antenna like the K6SE flag, which is as far removed
from the power lines as possible. The slight loss of directivity may be the
lesser of two evils.
You should be able to pick up some directivity by erecting two flags,
broadside to the chosen direction, and driving them in phase (i.e.
horizontal stacking). The antenna would then have a fixed direction, but
this is no different to the beverage.
73,
Peter VK3APN
pnesbit@melbpc.org.au
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