Re the recent discussion of flash-overs of guy insulators: (I'm behind on my
reading.)
At some of our high power MW facilities around the globe, flash-overs across
even very long antenna tower guy insulators caused by thunderstorms and by
atmospheric charges in very dry climates cause major problems. In some cases,
we have attached heavy duty RF chokes across the insulators. In others, we use
heavy duty high value resistors across the insulators. Both seem to work well.
It appears to me that the resistors have been more prone to failure than the
RF chokes. The RF chokes I have seen are much larger than the resistors and
contribute much more weigh and wind load. (These are on the guys of towers of
AM band systems operating at power levels of around 500 to 600 KW.)
We do this to avoid tripping off of the transmitters due to the impedance
shift caused by the flash-overs. I don't think it would be worth the expense
and effort to do this for an amateur radio antenna. I just thought it might be
interesting to some.
73,
Charles - S9SS
IBB (VOA)
---------------------------
BTW - I am now officially extended an additional 10 months in Sao Tome to
take me up to my retirement at the end of February 2007.
We are in a season of very high thunderstorm activity here, so reception on
160M has been hopeless for many weeks.
---------------------------------
Talk is cheap. Use Yahoo! Messenger to make PC-to-Phone calls. Great rates
starting at 1¢/min.
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