Re: [IRCA] Short antenna radials

[Tom Dimeo <am@xxxxxxxxx>]

AM antenna systems (especially directionals) are fascinating
to me. Below is a post from about two years ago that was on
another list where Franklin antenna systems were being
discussed. This post is about KFBK 1530.

I think the other true Franklin in the United States was at
WNBF 1290 Binghamton New York. I don't think it is being used
now because of the center insulator failing in some way.

Tom

** Begin Quote **
The two towers are used at all times (DA-2, one of the few
Class As to operate in this mode).

Both are 180 degrees over 180 degrees, a total of 360
degrees, so these are true Franklins (only one other exists
in the U.S., and it is ND-D).

The efficiency of each is 510 mV/m/kW at 1 km, which is about
99 kW out from 50 kW in.

The feed system is also home-built, using not the usual, for
50 kW, six wires (two central wires plus four surrounding
wires), but EIGHT wires (two central wires plus six
surrounding wires).

This system is still in place and is used 24/7/365 by one of
California's six Class As.

The feed system incorporates a matching system at the base,
horizontal to the vertical tower, and a vertical run up
one-half of  the tower height of nearly 640 feet to the
sectionalizing insulator where a network is present.

This vertical run is also eight wires.

Legend has it that the FCC inspector demanded that a ground
system be installed, and I guess one was, but it was very
soon abandoned.

There is no longer any strap from the bottom of the base
insulator to what would be the "ground".
** End Quote **

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