Thursday, 19 June 2014

NDB 'CLE' Weekend


The 'AP' NDB - Active Pass, Mayne Island, BC (378 KHz)

This weekend is the monthly 'Combined Listening Event' or 'CLE'. It is in fact, CLE # 183!

A 'CLE' is a worldwide listening event whereby NDB hunters all focus their attention on a specified 15KHz slice of the NDB band. 'NDB's are low-powered LF transmitters, usually located near airport runways, to aid pilots in navigation.

Listeners have three nights in which to try and log all of the NDBs that they can identify and report to the activity organizer, Brian Keyte G3SIA, in Surrey, England. Although the CLE activity is administered through Yahoo's NDBList Group, it is largely the work of one man, Brian, who decides which frequencies will be covered as well as tabulates all of the results in great detail. The CLE is not a contest activity but rather a means of keeping track of which beacons are still active and which ones may have gone silent since the last listening event on those particular frequencies. The frequency range for CLE183 is 320.0 - 334.9 KHz.

All of the results eventually end up in 'RNA' or 'REU' the master lists of active NDBs worldwide. This superb resource is operated by Martin Francis of Richmond Hill, Ontario. Updates to the list are made by Mark Moulding, KU7Z in Ogden, Utah. It truly is an international affair but runs very smoothly. The active and very friendly Yahoo Group is a great place to meet others interested in NDB DXing and is a good place to get started if you harbour any interest in LF DXing.

Be warned however, that NDB DXing is highly addictive! It almost seems that NDB's were made purposely for DXers since they do nothing but repeat their call letter IDENT endlessly, in reasonably slow CW. Most NDB's in the U.S.A. run about 25 Watts while those in Canada are usually higher power, especially the further north they go. Surprisingly, these LF signals will often propagate for thousands of miles under good conditions, further fuelling the addiction.

As an example, here is a recording that I made from Mayne Island, B.C., of 'UP', an NDB located in  Upernavik, Greenland and transmitting on 399 KHz.

I'll blog more about NDB DXing at a later time but meanwhile, it's still not too late to get in on the fun of this weekend's CLE183 listening event!  More CLE details may be found here.

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