Tom,
Thanks for the report. Perhaps your failure was due to moisture trapped
within the tape. I've always recommended NOT enclosing the cores, but
primarily for reasons of improved dissipation. FWIW, I've never heard of
a big multi-core choke overheating on a resonant antenna that isn't
badly unbalanced. I HAVE fried a single core bifilar choke under very
high duty cycle, legal limit operation that didn't have a second coax
choke farther down the line, and another on a dipole that had broken in
a storm -- I transmitted high power to it before I realized that. That
experience caused me to de-rate those single-core bifilar chokes to
about 500W, and to urge the use of a second choke for legal limit. That
recommendation is in the latest version of k9yc.com/RFI-Ham.pdf, updated
about a year ago.
Having spent 42 years in Chicago and prior years in OH and WV, I fully
appreciate issues with cold WX. I would greatly appreciate feedback from
those with experience, both positive and negative, with the chokes I've
recommended. Please DO include details of the antenna system -- type of
antenna (resonant dipole, beam, vertical), feedline used, where the
choke was placed, details of the choke, and any of other chokes in the
line.
73, Jim K9YC
On 6/29/2017 1:03 PM, Tom Frenaye wrote:
At 01:50 PM 6/29/2017, Jim Brown wrote:
Since I first published this work around 2007, I've yet to receive word of
problems from moisture, except a single report of cracking from freeze/thaw
with multiple cores. That's only one report in 9 years.
Jim -
Add me to the list, I've had cores disintegrate over the years. I use several
them at the base of my 80 and 160 4-square verticals, wrapped in electrical
tape to hold them together. The problem could have been freeze/thaw cycles,
or heating when one of the verticals detunes when it breaks and I didn't notice
the problem on the shack end.
I suspect those of us in ice/snow country see it more often than the San Jose
area does... Haven't found a good solution yet, I have trouble imaging that
the addition of a box and associated connectors, caulking and hardware will be
more reliable over time.
-- Tom
--------------------------------------------------------------------------------------------------------------------
e-mail: frenaye@pcnet.com YCCC --> http://www.yccc.org/
Tom Frenaye, K1KI, P O Box J, West Suffield CT 06093 Phone: 860-668-5444
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