I have always been and for the foreseeable future will probably have
to remain a cheapskate. It's the only way to erect big antennas on a
small budget! So, several coax cable capacitors have been pressed
into service at my station.
I have found that stripping about 25 mm (114/115") off the end of the
jacket, and then removing the braid from that portion before using
the "capacitor" precludes arcing at the end. It is sometimes also
necessary to suspend the coax away from grounded metal bits, as the
breakdown voltage for the jacket is considerably lower than for the
dielectric between conductors. I have had arcing between the braid
and the tower. I have used wooden blocks and some old bicycle tube
to insert between the capacitor and the tower, and the resulting
installation has been in service for 7 years at two locations,
without further maintenance.
Bottom line: Coaxial capacitors are hard to tune, and require some
tweaking before they work, but they offer unbeatable value for money
and low maintenance.
Chris R. Burger
ZS6EZ
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