Topband: remotely-controlled Beverage termination

[Mark Connelly]

Dave (W0FLS) said "I have experimented with changes in termination values
and have never found it to be a very critical issue based on actual measured
empirical performance."  The difference between my observations and Dave's
may be that the max/min frequency ratio on 160 is only 1.1 (2000/1800)
versus a ratio of 3.2 for AM BCB (1700/530).

Over small changes in frequency, optimum terminating resistance doesn't
change much, at least on a given day.  Over the long term there could still
be a benefit to an adjustable termination because soil moisture,
temperature, snow cover, leaves (or absence thereof), etc. could affect the
value required, even at a specific frequency.  

If there is a reactive component to the grounding scheme at the end of the
Beverage, that could introduce some frequency-dependent influences on the
optimum series resistance required.  In Newfoundland, the ground at the
shore was rocky and a combination of radials and ground rods was used at the
termination of the 1 km "Brazil Beverage": it's quite likely that the
radials acted as antennas or exhibited capacitive or inductive reactance to
ground, in addition to resistance, at various frequencies.

Mark, WA1ION







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