[TowerTalk] Replacing Linear Loading on Force 12 40/20

[Keith Dutson]

I have two F12 C-4XL antennas.  The linear loading design of the 40 meter
elements proved efficient, but resulted in discovery of a major mechanical
issue: it was easily damaged in high wind areas.  Although not observed, I
believe the failure was caused by vibrations, which affected all mechanical
joints.

Tom N6BT recognized this problem and subsequently offered a conversion kit
to replace this loading system with loading coils.  A relay at the feed
point adds inductance to lower resonant frequency to the CW portion of the
band.  Two of these kits were purchased.  One was installed and successfully
tested at 20 feet.  It is currently on the ground, in pieces, awaiting
cleanup, assembly and installation.  The other antenna is at the top of the
tower, and will be taken down for conversion.  I am thinking about tuning
one for CW and the other for SSB, thus eliminating the relays and control
cables.  A WX0B Stack Match will connect the two antennas for operation.

73, Keith NM5G

-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces at contesting.com] On Behalf Of Ray
Conrad NM2O
Sent: Saturday, November 4, 2017 9:56 PM
To: towertalk at contesting.com
Subject: [TowerTalk] Replacing Linear Loading on Force 12 40/20

I have a Force 12 40/20. The 40 Meters is a two element beam, using linear
loading. The loading is made from coperweld wire. I'm in NNY and subject to
icing each winter.


Has anyone converted to a loading coil to replace the linear loading?


The result ould be similar to the Cushcraft 2 el 40 Meter that uses a
loading coil.


73,

Ray

NM2O

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