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Operating low power from the field takes some preparation,
perhaps, especially with antennas. There are so many
trade-offs to consider! Higher and bigger is better,
especially when running low power. I don't see much
sense in operating five watts into a low efficiency
radiator!
33 feet is plenty of height for 10-20 meters and can
be adequate on 40 meters, but now we need an efficient
antenna, one antenna for all these bands, that is light!
We have two. both are made with 22 gauge woven wire,
insulated for further strength and so if it brushes
a branch, there won't be any detuning as a result. Make
no mistake, they require a tuner on all bands. Don't
leave home without one!
One antenna is a homemade G5RV. The flat top is 51
feet long. The stub is 16 feet of twin lead, with a
female BNC connector mounted on the bottom. Loops are
attached to the twin lead with hot glue so the line
is controlled by the mast. The flat-top is pulled out
by light weight mason's line fitted with fishing swivels
and snaps. I used no observable insulator which will
be fine at five watts if it doesn't rain on the mason's
line. This antenna is a dipole on 40 meters, almost
a double zepp on 20 meters and exhibits broadside gain
on all the higher bands.
The other antenna is a triangular loop, top open and
attached to 16 feet of twin lead, also controlled with
attached loops. This antenna is a full wave loop on
40 meters, but a bi-square gain antenna on 20 meters.
It exhibits broadside gain on 10-20 meters. We fed it
at the bottom of the loop through a homemade current
balun mounted inside a one inch diameter short piece
of pvc.
Each antenna weighs only ounces, cost only a few dollars
to build, and goes up in about ten minutes. Later reports
from other participants in the FYBO QRP activity were
that we had among the strongest signals on all bands
all day long.
Lest there be any doubts about the usefullness of CW,
we made 120 CW contacts during the few hours of the
activity, and five SSB contacts. When running portable
low power, CW will get through much more readily. It
is an investment that pays big dividends.
73,
Fred KT5X
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