Hi Contesters,
it=92s time for me to set up a new cubical quad antenna. After 15 years
my good old HYGAIN 244 quad passed away due to storms and corrosion.
The output of my cubical quad manufacturers search brought the result
that HY GAIN don=92t longer produce the quad. There are several quad
manufacturers in business. So I ordered some catalogues. Currently I
have two catalogues from LBA (Lightning Bolt Antennas) and a company
called CUBEX. I intend to buy a 5 band quad antenna. Both
manufacturers offer 5 band quads. LBA quads are the cheaper ones. With
my HY GAIN 244 quad it was no problem to feed the antenna with 1 coax
cable for 10/15 and 20 m. This quad worked with a superb gamma
matching whitout interaction.
LBA and Cubex quads are availlable with a matching transformer.The
antenna is fed with a single feed line. It has a balumn/transformer
arrangement that is evidently a toroid 1:1 arrangement with longscrews
sticking out where you put the elements on and have washers between
them. Also an SO-259 coax fitting for the coax to connect to. Simple
and very effective.
KI7M reported me that one thing !SURPRIZED! him about the LBA quad,
when he put it up all the bands had near perfect SWR! He has never
seen this with any other quad. It makes him want to remove the
transformer and feed the elements direct with the coax to see what
difference that might make. Just too good to be true.
K5ESW reported:
There is probably interaction. When you consider that a 20M element
will be two wavelengths on 10M, you can see why. The 20M element will
have an impedance on 10 that will be a close match, and therefore take
current.
Since all driven elements are connected together, current will flow
from the source into each element depending on the impedance at the
particular frequence of the source.
The question he has not yet answered, is what is the interraction, of
just having the elements there (not physically connected).
He also found some interraction at 12M, but not as bad as on 10M.
So I=92m a little bit confused. Does anybody made the same experiences
with using a matching transformer?? Are there any other quad producers
offering quads with gamma match?? Is a matching transformer as good as
single feed lines for each band? If the machting transformer effects
the gain of the quad it is inevitable for me to install a remote
switch to avoid five additional coax cables.
Your comments are apreciated very much!
vy 73 de DL6RDE/AA1KD, Charlie
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