[Elecraft] OCF antennas and baluns??

[George, W5YR]

In those "old days" they used r-f ammeters suspended by insulated wire from
the antenna and inductively coupled to measure the currents on either side
of the tap point. The tap point itself could be slid along the wire. After
adjustment for equal or nearly equal currents, the wire was soldered on. And
operation began.

It is necessary to remember that back in those days it was not at all
uncommon for a station to operate on a single frequency at all times. A
single crystal controlled oscillator was used and "everyone" knew who had
which frequency. The idea of moving around was unheard of until crystals got
cheap enough to own more than one and rudimentary VFO's became relatively
stable enough to be useful (near the end of the 30's).

Quite a different world back then!

73, George W5YR
w5yr@att.net


----- Original Message ----- 
From: "Ron D'Eau Claire" <rondec@easystreet.com>
To: <elecraft@mailman.qth.net>
Sent: Friday, December 19, 2003 6:27 PM
Subject: RE: [Elecraft] OCF antennas and baluns??


From what I've read, Windom's plan was to match the single wire feed
impedance on the horizontal dipole. That way it would have no standing waves
and so would not radiate. Normally, that point was established by monitoring
the current in the horizontal dipole on either side of the single wire, and
adjusting it so the currents were the same. That indicated that the feed
wire had no effect on the dipole current, and so had no standing waves.

Of course, even if the Windom feed WAS correctly set for no standing waves,
it was good on only ONE frequency! On any other frequency the wire radiated
- usually quite a lot.

Pretty soon no one cared much about finding the "magic spot" and simply
guesstimated the position of the wire at some percentage of the length from
the center of the dipole and accepted the feeder radiation as part of the
deal.

Ron AC7AC

-----Original Message-----
Remember the true old Windom design was a single wire feed, and thus surely
radiated from both the wire feeder and the flat top.   He was attempting to
find a tap setting on the flat top that would more easily load on multibands
with the old transmitters of his day.

Stuart
K5KVH

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