Hunting For NDBs In CLE256

CLE 256 will be held this coming weekend and will be somewhat different than normal.

'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 ... but this one is a little different.

This event has been organized around the Maidenhead Locator system and will challenge hunters to log beacons based upon the beacon's FIELD designation. Listeners should seek to log a maximum of five NDBs in each GRID FIELD.

The grid field is actually the first two letters of the grid locator, such as 'CN', 'FN', 'DM' etc., as seen in the map above. Each field itself is divided into 100 GRID SQUARES, but individual grid squares are not relevant for this CLE ... only the fields.

Most amateurs that operate on the VHF bands are very familiar with the 'grid square locator' system and many VHF operating awards and events are focused on working different grid squares. This may all be a new adventure for many non-VHF DXers but it does present a whole new way of keeping track of your catches.

I have always kept track of the grid square locator for all NDB signals that I hear and often find that a signal being heard from one particular square will lead to other beacons being heard (often new catches) from adjacent squares, while propagation is spotlighting that region ... it often pays to keep a grid square map handy while you search the band!

If you are not familiar with the grid square system, it's all pretty simple and this CLE only focuses on the largest part of the system, the FIELD. The first thing you should do is determine your own grid FIELD location, which, for North America, can be found very easily from the map above or anywhere in the world on K7FRY's locator map.

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:

Hello all

Here are the Final Details for this weekend's special DX Listening Event.
We'll be listening for up to 5 NDBs in as many Locator FIELDS as we can.
Fields are the first 2 letters of the 6 character locators ('Grid Square').

A World map of all the locator Fields is shown below:

(click map to expand)

You can see, for example, that Field IO includes most of the British Isles.

    Days:     Friday 22nd May – Monday 25th May

    Times:    Midday on Friday to Midday on Monday, LOCAL time at the RX

    QRG:      Normal LF/MF frequencies (190 - 1740 kHz)
    Target:     UP TO 5 NORMAL NDBs IN EACH LOCATOR FIELD (see below)
                    (not DGPS, NAVTEX, Amateur or UNIDs)

    Please also log YOUR NEAREST ACTIVE NDB - that will probably be one
    of the five in your own Field.

Please post your CLE log to the List in a plain text email if possible, with
'CLE256 FINAL' at the start of its title and showing on each log line:

    The full Date ( e.g. 2020-05-22, etc., or just the day number 22 )
    UTC  (The day changes at 00:00 UTC).
    kHz - the NDB's nominal published frequency
    The Call Ident.

As always, put those FOUR MAIN ITEMS FIRST on each log line, with any other optional details such as location and distance LATER in the same line.
There is no need to show the locator Fields (the harvester program will work out all of them and the nearest NDB you logged).

Your log will be easier to read if you group your loggings by Locator Field
and leave a blank separator line between the groups of up to 5 lines for each Field.  If you wish, you could add the 2-letter Field ident (NOTHING ELSE) at the start of each of the separator lines.

UNIDs that you come across may also be of interest - in a SEPARATE part
of your log please.

If you send interim logs, please make sure that you also send a 'FINAL' log
showing ALL your loggings for the CLE.

We will send the usual 'Any More Logs?' email to NDB List at about
19:00 UTC on Tuesday so you can see that your log has been found OK.

Do make sure that your Final log has arrived on the list by 08:00 UTC on
Wednesday 27th May at the very latest.

Joachim and I hope to complete the combined results within two days or so.


It will really help you to plan your listening if you go to the excellent
Rxx Database  (Europe)
(Replace the 'reu' by 'rna' if you are in North America, 'rww' elsewhere)

THE KEY PLACE to start entering details of what you want is 'Signal

Locations - GSQs'.

Put a 2-letter FIELD id in that box to see all the NDBs in that Field that
have been logged from your part of the World (i.e. EU or NA or other).
You could choose to alter the resulting list in lots of different ways:

 Select 'Only active' (bottom right).

 Enter your own Country or State in 'Heard Here'.

 Select a specific listener (yourself?) in 'Logged by' – BUT you might then miss a beacon that you haven’t heard so far.

  Add extra locator Field(s) in the 'GSQs' box, separated by blanks.

   - In ANY of the above, you can select 'Map' instead of 'List' (top right)

  Add your own full locator (6 characters) in 'Distance - From GSQ' to see the distances and bearings from your location.

  In 'Sort By' (bottom line) select GSQ.

Getting cleverer (!) you could use the wild card _ (an underscore) to see
details of all Fields with the same column of Longitude or row of Latitude
e.g.  I_  selects all of locator column I (0  to 20 degrees west),  _O would give all of row O (50 to 60 degrees north).

Good Listening


From: Brian Keyte G3SIA                ndbcle'at'
Location: Surrey, SE England          (CLE coordinator)


  As usual a few of us may choose to listen via a REMOTE RECEIVER,
  with permission if required - its own location will be their temporary
  home Field and its nearest active NDB should be logged, if known.

  A remote listener may NOT also use another receiver, whether local
  or remote, to obtain further 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 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 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 and good hunting!
Steve McDonald, VE7SL, is a regular contributor to and writes from British Columbia, Canada. Contact him at [email protected].

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