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- Subject: Re: Wellbrook Large Aperture Loop Antenna ALA100LN
- From: Mark Connelly <markwa1ion@xxxxxxx>
- Date: Tue, 2 Feb 2016 22:57:57 -0500
- Delivered-to: irca@xxxxxxxxxxxxxxxx
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Flags, Deltas, and SuperLoops can indeed be changed to bidirectional (figure-of-8) from cardioid by shorting out the termination resistor.
I do that here from time to time on N-S loop when it's more important to null NYC (W) instead of Boston / Portland (N) when DXing Latin America (S).
Depending on the size of the loop, you might want to go to a 1:1 transformer at the feedpoint for bidirectional instead of the usual one in the 9:1 to 16:1 range used for the cardioid set-up.
10m high by 11m long loop here does not need any amplification either in cardioid or figure-of-8 mode.
Being near the seashore probably means that the signals are "beefy" enough most of the time.
Not sure why such a simple antenna needs to be purchased, especially if you don't need to amplify. You just need some wire, supports, easily-built RF transformer, and feedline to the shack. Maybe about $40 worth of parts altogether.
Mark Connelly, WA1ION
South Yarmouth, MA
<<
?Yes, the ALA100LN may be Wellbrook's "jack of all trades" in my opinion.?
Also up for consideration though is the FLG100LN. A pair of deltas with
these modules also make an excellent phased system in a reasonable amount
of space (40m separation is recommended) compared to a Beverage's space
requirements. Of course, you can phase the ALA100LNs also.
The Wellbrook phaser works well with very little tweaking needed across the
MW band, once phase and gain are set. Other phasers can work but will need
readjustment every 100-200 kHz or so. Wellbrook's phaser is best for
broadband SDR recording with a phased loop array.
?Hmm... I just took a look at Wellbrook's web site, and the phasers are
nowhere to be found. Perhaps they'll still offer them by special order??
A friend of mine who does considerable EZNEC modeling ?has shown that the
FLG100LN can also work well in "zero ohms" mode (i.e., no termination
resistor) and essentially becomes a bidirectional loop as with the
ALA100LN. Wellbrook doesn't advertise the FLG100LN for use without
termination, but the computer models and actual testing reveal this extra
benefit.
73,
Guy Atkins
Puyallup, WA
>>
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