Hunting For NDBs In CLE268

LF-336kHz courtesy:

It's CLE time! 'CLE's are 'Co-ordinated  Listening Events, and NDB DXers around the world focus their listening time on one small slice of  the NDB spectrum.

It's another unique one again with a 200kHz window -- the hunting ground is 275.0 - 475kHz.

Propagation on MF has been both hot and cold for the past few weeks, seemingly depending on where you live and the amount of geomagnetic activity affecting your region. As well, the Sun has been throwing a lot of Coronal Hole Streams toward earth which may or may not affect this weekend's propagation ... but this is all part of the radio-magic fun.

A 'challenge target' for listeners in North America is LF - 336kHz in La Salle, Manitoba, in the southern central part of the province. Even though running just 50 watts, it's widely heard throughout North America and is a good target for listeners everywhere. Listen for LF's upper sideband on 336.390 kHz.

When tuning for NDBs, put your receiver in the CW mode and listen for the NDB's CW identifier, repeated every few seconds. Listen for U.S. NDB identifiers approximately 1 kHz higher or lower than the published transmitted frequency since these beacons are modulated with a 1020 Hz tone approximately.

For example, 'AA' near Fargo, ND, transmits on 365 kHz and its upper sideband CW identifier is tuned at 366.025 kHz while its lower sideband CW ident can be tuned at 363.946 kHz. Its USB tone is actually 1025 Hz while its LSB tone is 1054 Hz.

Often, one sideband will be much stronger than the other so if you don't hear the first one, try listening on the other sideband.

Canadian NDBs normally have an USB tone only, usually very close to 400 Hz. They also have a long dash (keydown) following the CW identifier.

All NDBs heard in North America will be listed in the RNA database (updated daily) while those heard in Europe may be found in the REU database. Beacons heard outside of these regions will be found in the RWW database. These databases have recently been re-vamped and are slicker than ever before!

From CLE coordinator Brian Keyte (G3SIA), comes the following CLE info:

 Hello all,

Our sixth special 'Channels Challenge' listening event is nearly here.
These are the full details.

    Days:      Friday 28 May - Monday 31 May
    Times:     Start and end at midday, your LOCAL time
    Range:     275 kHz - 425 kHz   (see below)
    Target:    Try to log ANY ONE NDB in each channel

The main challenge is to try and log ONE NDB in each of the
151 channels in the range from 275 kHz up to 425 kHz inclusive.
The last time we did this was in CLE248 in September 2019.

The 'channel' means the NDB's NOMINAL (published) frequency.
(It may not be quite where you hear the Morse ident of course). 
In parts of the World some NDBs are on intermediate frequencies,
such as 321.5 kHz.  Logging an NDB on a 'half frequency' would be OK.
  E.g. OK for channel 321 would be  EITHER  one on 321.0 kHz
                OR  one on 321.5 (shown as 321.5 in your log of course).

Each NDB must be a 'normal' one - no DGPS, NAVTEX or amateur.
(If you hear any UNIDs, please show them in a separate list).

So it means a highest possible total of 151 CLE loggings in all - and that
will surely be impossible for everyone!

If you have extra time and want to make the challenge more interesting you
could include NDBs which:

   Give you the greatest number of DIFFERENT RADIO COUNTRIES heard.
   (See our Countries list at

    Each State/Province in USA, CAN and AUS is a separate radio country)
   OR  give the greatest TOTAL DISTANCE from you to all of the NDBs.
   OR  include the greatest number of MIDDAY LOGGINGS
          i.e. heard within 2 hours of midday by your local clock time.

Send your 'Final' CLE log to the List, ideally as a plain text email (not in
an attachment) and, IMPORTANT, with CLE268 and FINAL at the start of its
Please show on EVERY LINE of your log:

   #   The full date or day no.  e.g. '2021-05-29' or just '29', etc.
          and UTC (the day changes at 00:00 UTC).
   #   kHz  - the beacon's nominal published frequency.
   #   The Call Ident.

Show those main items FIRST on every line, before other optional details
such as Location, Distance, Offsets, Cycle times, etc.

Tell us your location of course and details of your receiver, aerial, etc.

We will send the usual 'Any More Logs?' email at about 19:00 UTC on Tuesday
so you can check that we have received your log OK.
Do make sure that your log has arrived on the List at the very latest by
08:00 UTC on Wednesday 2 June.
We'll try to complete making the combined results within a day or two.

Good hunting,
   Brian and Joachim
From:      Brian Keyte G3SIA       [email protected]
Location:  Surrey,  SE England      (CLE coordinator)

(Reminder:   You could use any ONE remote receiver for your loggings,
stating its location and owner - with their permission if required.
A remote listener may NOT also use another receiver, whether local or
remote, to obtain further loggings for the same CLE).

If you are interested in some remote listening - maybe due to local difficulties - you could use any one remote receiver for your loggings, stating its location and with the owner's permission if required.( e.g. see ) A remote listener may NOT also use another receiver, local or remote, to make more loggings for the same CLE.

These listening events serve several purposes. They

• determine, worldwide, which beacons are actually in service and on-the-air so the newly-re-vamped Rxx online database can be kept up-to-date

• determine, worldwide, which beacons are out-of-service or have gone silent since the last CLE covering this range

• will indicate the state of propagation conditions at the various participant locations

• will give you an indication of how well your LF/MF receiving system is working

• give participants a fun yet challenging activity to keep their listening skills honed

Final details can be found at the NDB List website, and worldwide results, for every participant, will be posted there a few days after the event.

The NDB List Group is a great place to learn more about the 'Art of NDB DXing' or to meet other DXers in your region. There is a lot of good information available there and new members are always very welcome. As well, you can follow the results of other CLE participants from night to night as propagation is always an active topic of discussion.

You need not be an NDB List member to participate in the CLEs and all reports, no matter how small, are of much value to the organizers.

Remember - 'First-time' logs are always VERY welcome!

Reports may be sent to the NDB List Group or e-mailed to CLE co-ordinator, Brian Keyte (G3SIA), whose address appears above. If you are a member of the group, all final results will also be e-mailed and posted there.

Please ... give the CLE a try ... then let us know what NDB's can be heard from your location! Your report can then be added to the worldwide database to help keep it up-to-date.

Have fun and good hunting!
Steve McDonald, VE7SL, is a regular contributor to and writes from British Columbia, Canada. Contact him at [email protected].

Leave a Comment

Subscribe FREE to's
Amateur Radio Newsletter
News, Opinion, Giveaways & More!

Join over 7,000 subscribers!
We never share your e-mail address.

Also available via RSS feed, Twitter, and Facebook.

Subscribe FREE to's
Amateur Radio Newsletter

We never share your e-mail address.

Do you like to write?
Interesting project to share?
Helpful tips and ideas for other hams?

Submit an article and we will review it for publication on!

Have a ham radio product or service?
Consider advertising on our site.

Are you a reporter covering ham radio?
Find ham radio experts for your story.

How to Set Up a Ham Radio Blog
Get started in less than 15 minutes!

  • Matt W1MST, Managing Editor

Sign up for our free
Amateur Radio Newsletter

Enter your e-mail address: