Hunting For NDB Pairs In CLE251

A fairly popular CLE event held around this time of the year is the "Noah's Ark" Holiday CLE!

It calls for listeners to hunt down and log pairs of NDBs from as many 'radio countries' as possible.

As explained below, in NA and Australia, states and provinces count as separate 'radio countries' thankfully.

For those unfamiliar with this monthly activity, a 'CLE' is a 'Co-ordinated Listening Event', as NDB DXers around the world focus their listening time on one small slice of the NDB spectrum.

If you've been meaning to participate in  CLE, then maybe this weekend is a fine time to try! We continue to have  a lot of first time submissions so you won't be alone!

As well, if you're trying to learn CW, copying NDBs is perfect practice as the identifier speed is generally slow and the letters are repeated again every few seconds!

This past week has seen a long period of great propagation quickly get worse with the arrival of another coronal hole stream. This is quickly abating and the ionosphere may well have fully recovered for the nine-day event.
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.

From CLE organizer Brian Keyte, G3SIA, comes the details:

Hello all

We hope you are looking forward to our "Noah's Ark" Holiday CLE – it
starts at midday on Christmas Day and you can listen at any times
from then right through to midday on Thursday 2nd January.
It's very straightforward. Just as the animals went into the Ark two by two,
so the Radio Countries' NDBs will go into our logs two by two.

    Days:     Wednesday 25th December to Thursday 2nd January
    Times:    Start and End at midday, your LOCAL TIME
    Target:   A maximum of TWO NDBs from each Radio Country
    Range:   190-1740 kHz

So during the course of the event we shall try to log TWO NDBs from each
of as many Radio Countries as we can - e.g. 2 from France, 2 from Spain,
2 from the Florida, 2 from Quebec, 2 from Brazil, 2 from New Zealand, etc.
Each Australian and USA State and each Canadian Province is a separate
Country.  For our full list see:
Each NDB making the pairs can be logged at any times during the event.
UNIDs, Amateur, DGPS and Navtex beacons are not included, but any
UNIDs can be shown in a separate 'non-CLE' list or in a separate email.

Noah didn't have single animals in the Ark, but if you can only log ONE
NDB from a Country, it will still be welcome in your log without a mate!

Everyone is asked to please listen for YOUR OWN NEAREST active NDB
and include it with the one other logging for that Country (if any).

For details of a country’s active NDBs go to
If you are listening from Europe or North America replace the rww by
reu or rna respectively.    Next to 'Locations' enter the State or Country
abbreviation(s), then select 'Only Active’ at the bottom.

Post your final, complete log to the List (please not in an attachment)
with CLE251 and FINAL in the Subject heading, to arrive at the very latest
by 09:00 UTC on Saturday 4th January.

As usual, please include on every line of your log:
    #  Date** and UTC (the day changes at 00:00 UTC)
    #  kHz (the nominal, published, frequency if possible)
    #  Call Ident

Those main log items must be shown FIRST with the country shown
LATER in the same line, together with any other (optional) details
such as location, offset and distance.

  The input program for REU/RNA/RWW does not allocate the month and year.
  The good people who enter the information for us then have to tell the
  program what month and year to use.  That is not a problem IF ALL
  So please help us by making sure you separate your December and
  January loggings, even if it breaks up some Noah pairs.

Where possible, we suggest that logs are in Radio Country order, instead
of in the usual kHz order, so that the country pairs appear together.

We'll send an ANY MORE LOGS? email at about 20:00 UTC on Friday 3rd
January showing whose logs we have found. Try to post your log to the
List before that  so you will get confirmation that it has arrived OK.

Good listening, everyone.  Enjoy the CLE.
And finally, radio or not, Joachim and I wish you a very HAPPY CHRISTMAS.

(CLE Coordinator)

Reminder 1:
This is an ideal event to help you qualify for one or more of Joe Miller's
attractive Award Certificates - they make great "wallpaper" for any
listening shack.  Joe, our Awards Coordinator, invites us to submit
requests. will take you to the
different web pages containing the advice you will need.
Certificates can be ordered direct from the REU-RNA-RWW database.
Now is a good time to apply with so many NDBs going off air.

Reminder 2:
You could use any ONE remote receiver for your loggings, stating its
location and owner - with their permission if required.
( e.g. see )
A remote listener may NOT also use another receiver, whether local
or remote, to obtain further loggings for the same CLE.

These monthly listening events serve several purposes. They:
  • determine, worldwide, which beacons are actually in service and on-the-air so the 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

The NDB List Group is a great place to learn more about the 'Art of NDB DXing' or to meet other listeners 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 good hunting and have a great Christmas!
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: