Thursday, 9 October 2014

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.


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.

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!


Anonymous said...

Steve - my 12' square loop is most
definitely wind challenged in the winter! John WG2XKA VT USA

Steve McDonald said...

That's what I'll be worried about myself until I can see how it behaves in a good blast. I have some Dacron ties on the two ends so I will tie it down when the winds come up and that should stabilize it somewhat.