[TenTec] Thanks but my antennas are fine :) Traps vs. tuner losses

[Stuart Rohre]

Caity,
It is a toss up whether to put the coil losses in a trap or in a tuner.
The tuner stays indoors, and thus likely will have fewer things to go lossy
from exposure to the elements that a trap endures.  Now it may be that
building traps from coax, will give you low loss traps.  Certainly, traps
should have low loss components.  This generally means have high Q parts,
and when you have a high Q circuit you sacrifice bandwidth on the band where
the trap is part of the antenna loading.
There are more parts to have loss in some traps than others.  Probably could
say same as there are L net tuners and Tee net tuners, plus Z match and
other parallel types.

The trap should not affect you on higher bands where it is acting as a choke
to RF currents.

I saw something in newest QST on a beam design, and its traps were supposed
to only have 0.2 dB loss.  The wire was quite a large diameter, although PVC
was used as the coil form.  PVC is OK in this application, but has higher
dissipation factor as a dielectric than say Polystyrene.

Usually, when you have limited space you have to compromise.  IF you can
drop the legs or the dipole at right angles, or use hat loading, you might
get the best of all worlds.  Shortened dipole, and no trap loss.  See
www.cebik.com and the Force 12 antennas web site for ideas on loading ends
of dipoles.  The rods used on the Sigma 5 short loaded vertical allow it to
work on 20 to 10m with only 12 foot height.

73,
Stuart
K5KVH