Topband: FEEDING AN END-FED LONGWIRE

[Tom Rauch]

> If you are talking about the "end-fed zepp" the unterminated feeder,
> sometimes called the "dead" feeder somewhat balances out the "live" feeder
> that connects to the end of the antenna.  While the balance is not perfect
> and cancellation is not complete, the feedline radiation is significantly
> less than with a simple one-wire vertical feeder ( which would qualify the
> antenna as an "inverted-L").

Radiation is only significantly reduced when the antenna is operated at a
frequency where the antenna is a very high impedance at the feed-end ....
and is best when the feedline is an odd quarter wave long. This is Zepp-like
condition, almost the same distribution as the J-pole copy of the old
antenna called the Zepp.

When the feeder is not an odd quarter wave long currents are often far from
equal, as is the case when the flat top does not present the required very
high impedance. Balance in the shack is pretty good when proper lengths are
involved and the tuner is a true ground independent design.

A point of false claims is with a balun on a tuner input to make a "balanced
tuner". Moving the balun to the INPUT of the tuner does not help balance at
all or make balun choking impedance less critical, contrary to what is
popularly claimed!!!!

73 Tom