Loop Listen

As Murphy would have it, and in spite of the low amount of solar activity, LF/MF propagation has been very poor since getting my new 10' x 20' loop in place. The few front-to-side nulling checks that I have done, have produced results varying from around 20db to 30db, depending upon the signal. I suspect the depth of null is also affected by the signal's arrival angle but there is still more to learn. The pattern seems to be very close to that of a typical circular loop...the classic figure-8 pattern illustrated below as shown on the Wellbrook data that came with my ALA100LN preamp.

Courtesy: http://www.wellbrook.uk.com

More typically, the null is around 21-22 db as shown on this test while listening to the ground wave carrier of the YZA ndb (236kHz) located in Ashcroft, B.C., about 150 miles to the NE. As expected, the null is fairly sharp and the front / rear lobe, fairly broad.


One short check at dusk, produced nice signals from  CJBC, the French-language station in Toronto. The past few nights it has been very strong but with a strong echo effect. I wonder if there is more than one CBC outlet here (860kHz), such as a low-power repeater, causing the echo.


At the same time, while still fairly light outside, WCCO in Minneapolis had a nice signal just before sunset.


No matter how poor conditions become, it seems that the Hinchinbrook (Alaska) ndb, 'ALJ' (233kHz), is always strong....looping north.



Courtesy: https://www.google.ca/maps
My apologies for the video quality. If you know of any software available for making full-screen Perseus video captures so that I might improve my technique, please let me know. Presently I am just capturing them on my I-Pad which leaves a lot of room for improvement.

Hopefully conditions will only get better as the season progresses and I am able to give the loop a good workout....before it gets too windy!
Steve McDonald, VE7SL, is a regular contributor to AmateurRadio.com and writes from British Columbia, Canada. Contact him at [email protected].

2 Responses to “Loop Listen”

  • Larry Faehling KL7IBV:

    It’s probably the same Nautel 1kw beacon that I put in up there in ’76 or ’77. It was the first NBD in that location to replace the old range (A/N) that was, from what I was told, was the 2nd to last range to be decommissioned in the U.S.A. ,the last being the San Francisco area range. I loaded it up on the only remaining range tower left standing, so it’s probably had a good ground system all these years. Of course, that was a long time ago, and could be another install completely.

  • Larry Faehling KL7IBV:

    The old range equipment was still in the building when I put that beacon in. It was under the authority of the Civil Aeronautics Board in the 1930’s, according to the plates on the equipment, which was huge.

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