>From KC4CLD:
> K9AY loops come from factory with pre-settings of 560, 1500 and 2700 Ohmz
> and the VTL5C2 is the perfect Vactrol covering these full values and more
> thru 5.5k.
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Lionel and all,
The K9AY Loop systems I am making have three selectable resistances:
560, 464 and 408 ohms -- the 1500 and 2700 ohm resistors are switched
in parallel with the 560 ohm resistor. These are the typical values that will
work best on 80, compromise 80/160, and 160, respectively, using the
antenna dimensions of the original QST article. The termination is frequency-
sensitive, although the 408 ohm termination is usually OK for BCB stations.
Higher frequencies (where the loop is electrically large) require the greatest
change in value, sometimes requiring an L or C in addition to R to get the
deepest null.
I will eventually have a version available with adjustable termination --
more testing is needed to see how the Vactrols hold up near a 1.5 kW
transmitter, or if something more robust is required.
73, Gary
K9AY
k9ay@k9ay.com
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