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Old April 21st 04, 09:39 AM
starman
 
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Dave wrote:

Starman,

I am no longer intending to use a folded dipole, or a dipole of any kind. I am currently planning to connect the conductors at the far end of the 300 ohm twinlead but only connect one side of the near end to the 300/75 ohm matching transformer. Will this not work? I don't need perfection, just reasonably good (I think.)

Thanks,

Dave


So you're going to use the twinlead as if it was a single wire. In that
case, you might as well connect the two wires in the near end too. There
isn't any advantage to keeping the wires of the near end seperated.
Connect the twinlead's near end to one wire of the high impedance side
(300-ohm) of the matching transformer (balun). The other wire on the
300-ohm side should go to a ground rod, IF you're building the antenna
design on the website I gave you. Otherwise connect the remaining
300-ohm wire to the shield of the coax. This will require some kind of
adapter, if the balun has a threaded female F-connector for the coax on
the low impedance side. A standard coax inline grounding adapter (block)
would work. These are made for connecting a ground wire to the coax
shield in a TV installation. This adapter has a female F-connector on
each end and a grounding screw on the outside of the 'block'. Connect
the remaining wire on the 300-ohm side to the ground screw on the
adapter block. If you use this kind of adapter you will also need
another adapter with a male F-connector on each end to connect the
ground adapter block to the threaded female side of the balun. You might
be able to find a coax grounding adapter which has a male F-connector on
one end and a female on the other end, along with the grounding
terminal. Then you wouldn't need two adapters.

The center wire of the coax goes to the low impedance side of the balun
which is the center hole of the threaded female F-connector on the
balun. The coax shield connects to the outside threads of that
F-connector, which would also go to the ground rod from the grounding
adapter, if you're making the website antenna.

All of the above assumes you're using a standard TV balun which has a
threaded female coax F-connector for the low impedance side and two
wires (pigtails) on the high side. You should install a male F-connector
on the balun end of the coax. In the previous post I advised against
using a TV balun because it will most likely attenuate signals below
about 10-Mhz. This means the lower shortwave bands and also the regular
AM(MW) band would be somewhat weaker but this might not be a problem,
depending on what frequencies/bands you want to hear best.



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