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CLE 237 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:

===============================================
Here are the Final Details for this weekend's DX Listening Event.

We'll be listening for NDBs in as many Locator FIELDS as we can.

Fields are the first 2 letters of the 6 character locators ('Grid Square').

    Days:     Friday 26th October – Monday 29th October
    Times:    Midday on Friday to Midday on Monday, your LOCAL* time
            *(NB Many of us will be changing our house clocks this weekend.
               UTC time, shown in our logs, continues unaffected by that)
    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 - it will probably be one of
the five in your own Field.

A World map of all the locator Fields is attached.  You can see, for
example, that Field IO includes most of the British Isles.

(click map to expand)

Please post your CLE log to the List in a plain text email if possible,
with 'CLE237' at the start of its title and showing on each log line:

     The full Date ( e.g. 2018-10-26, etc., or just the day number 26 )
     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 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 separator line.

Any UNIDs that you come across will 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
18:00 UTC on Tuesday so you can check that your log has been found OK.
Do make sure that your Final log has arrived on the list by 09:00 UTC
on Wednesday 31st October at the very latest.
Joachim and I hope to complete the combined results within two days.


PLANNING YOUR LISTENING

It will really help you to plan your listening if you go to the excellent
Rxx Database  https://www.classaxe.com/dx/ndb/reu
(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 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 missa 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 the 'Distance - From GSQ' box 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

73    Brian
---------------------------------------------------------------------
From: Brian Keyte G3SIA                ndbcle'at'gmail.com
Location: Surrey, SE England          (CLE coordinator)
---------------------------------------------------------------------

(As usual a handful of us may choose to listen via a remote receiver
with permission if required - its own location will be their temporary
home Field).
A remote listener may NOT also use another receiver, whether local
or remote, to obtain further loggings for the same CLE.

===================================================

courtesy: https://sdo.gsfc.nasa.gov/

It seems that for the CLE236 listeners in western North America, my worst fears came true. The week preceding last weekend's listening event had seen great MF propagation and quiet geomagnetic conditions.




On Friday evening, shortly after the start, a geomagnetic storm commenced, with K-levels reaching 5-7 at various stations ... pretty much sounding the death knell once again. It seems more than coincidental that almost every CLE in the past few years has seen horrific geomagnetic conditions in lock-step with our scheduled monthly events!

Since there were no active regions on the Sun at the time, I suspect, as mentioned in my last blog, that we were victimized by a sudden spurt from the same coronal hole that whacked us last month, as it lined-up once again on its monthly reappearance. Arriving on Friday evening as sunset approached, the effects seemed to spare the rest of North America (and Europe), as western listeners were the only ones reporting poor propagation. As well, lightning noise, often abating by this time of the year, created havoc for many listeners ... even those with good propagation.

I can only hope that next month's event will see a major improvement in noise levels as well as in propagation quality. Hopefully, that pesky coronal hole will have closed itself by then!

On top of the above mentioned challenges, CLE236's frequency range was smack on top of my local pest, AP-378, whose antenna is less than one mile from my own antennas. Having an S9 +60db signal in the middle of the narrow CLE range does make for challenging listening. My 10' x 20' loop knocked AP's signal down about 25db, allowing me to hear the following signals, some only barely.


 
See you in CLE237.

AP-378 Mayne Island, BC

How time flies. Once again it's a CLE weekend. It seems like the last one was just a week ago!




 '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.

This time the hunting ground is the 15 kHz slice from 370.0 - 384.9 kHz.

This is a somewhat dreaded range for me since my local blowtorch NDB, 'AP' (378 kHz), sits right in the middle of the range. 'AP' is located at the entrance to Active Pass, the main ferry route to Vancouver Island, and the antenna is about 3/4 of a mile down the beach from me. Needless to say, the beacon is about 40db over S9! With careful loop nulling, I can reduce this by about 25db but it's still an enormous signal to deal with.

Hopefully you can put 'AP' in your own log this weekend but its 25-watt signal will be much weaker for you. It's been logged as far east as Illinois and with your receiver in the CW mode, can be found on 378.399 kHz.

All too often our CLE weekends get hammered by geomagnetic disturbances, possibly because our monthly schedule syncs up nicely with the Sun's rotation and the disturbance from the previous month once again rotates into position. Conditions this time surely can't be much worse than for our previous event and today's mid-week check looks promising.

courtesy: NOAA

courtesy: NOAA

Things seem geomagnetically quiet at the moment so lets hope they stay that way. LF and MF propagation can often be amazing in the fall and as summer storms start to dissipate, the band can become much less noisy.

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


Hi all,

Please join us in our 236th coordinated Listening Event which starts
this Friday and celebrates the arrival of the Equinox this weekend.
CLEs are not contests - if you enjoy taking part you will be a winner!

    Days:    Friday 21 September - Monday 24 September
    Times:   Start and end at midday, LOCAL TIME at the receiver
    Range:   370 - 384.9 kHz

Just log all the NDBs that you can identify with their nominal (listed)
frequencies in the range (it includes 370 kHz, but not 385 kHz)
plus any UNIDs that you come across there.

Please send your CLE log to the List in a plain text email if possible
(not in an attachment) with CLE236 and FINAL at the start of its title.
Show on each log line:
    # The date (e.g. 2018-09-21, etc., or just 21) and UTC
          (the date changes at 00:00 UTC)
    # kHz  (the nominal published frequency, if known)
    # The Call Ident.

Show those main items FIRST - other optional details such as Location
and Distance go LATER in the same line. 
If you send interim logs, please also send a 'FINAL' (complete) log.

As always, tell us your own location and brief details of the equipment
that you were using during the weekend.

Joachim or I will send the usual 'Any More Logs?' email at about 17:00
UTC on Tuesday - you can then check that your log has been found OK.
All logs must arrive on the list at the very latest by 08:00 UTC on
Wednesday 26th September.  We hope to complete making the combined
results within a day or two.

To help you to plan your listening, seeklists and maps for your part of the
World are available via the CLE page  http://www.ndblist.info/cle.htm

Good listening - enjoy the CLE.
    Brian
------------------------------------------------------------------
From:     Brian Keyte G3SIA         ndbcle'at'gmail.com
Location:  Surrey, SE England       (CLE coordinator)
------------------------------------------------------------------

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. A remote listener may NOT also use another receiver, local or remote, to make further loggings for the same CLE.
 -------------------------------------------------------------------

BF-362 Seattle

courtesy: NOAA

My log consisted of 30 stations, with all but two from Friday night before the storm. As usual, the receiver was a Perseus SDR and an 'Inverted-L', resonated at 300 kHz.
25 12:00  350     SWU   Idaho Falls, ID, USA
25 08:00  350     RG   Oklahoma City, OK, USA
25 07:00  350     NY   Enderby, BC, CAN
25 07:00  351     YKQ   Waskaganish, QC, CAN
26 12:00  352     RG   Rarotonga IAP, CKS
25 07:00  353     ZXY   Whitehorse, YT, CAN
25 08:00  353     PG   Portage La Prairie, MB, CAN
25 13:00  353     LLD   Lanai Island, HWA
25 07:00  353     AL   Dixie, WA, USA
25 12:00  355     AUB   King Salmon, ALS
25 12:00  356     ZXE   Saskatoon, SK, CAN
25 08:00  356     ZF   Yellowknife, NT, CAN
25 08:00  356     PND   Portland, OR, USA
25 08:00  356     ON   Penticton, BC, CAN
25 12:00  356     MEF   Medford, OR, USA
25 09:00  358     SIT   Sitka, ALS
25 09:00  359     YQZ   Quesnel, BC, CAN
25 09:00  359     YAZ   Tofino, BC, CAN
25 07:00  361     HI   Holman, NT, CAN
25 07:00  361     E3   Wabasca, AB, CAN
25 07:00  362     YZS    Coral Harbour, NU, CAN
25 07:00  362     RPX   Roundup, MT, USA
25 07:00  362     BF   Seattle, WA, USA
25 08:00  362     6T   Foremost, AB, CAN
25 07:00  365     YGZ   Grise Fiord, NU, CAN
25 12:00  365     MA   Mayo, YT, CAN
27 08:00  365     DPY   Deer Park, WA, USA
25 07:00  365     AA   Harwood, MN, USA
25 12:00  368     ZP   Sandspit, BC, CAN
25 12:00  368     VX   Dafoe, SK, CAN

The results from ALL participants may be viewed here.

BF-362 courtesy: Steven M O'Kelley

This coming weekend will see another monthly CLE challenge. This time the hunting grounds will be 350.0 - 369.9 kHz.

 


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.

A really good challenge in this one is to hear BF-362, located in Seattle, Washington. I suspect that it's a 25-watter but is rarely logged outside of the Pacific Northwest region. If you are east of Montana and can hear it, your system is working well!

Listen for BF's  upper-sideband CW identifier (with your receiver in the CW mode) on 363.030 kHz while its lower-sideband can be heard on 360.943 kHz.

Although we are getting ever-closer to the fall DX season, lightning storms may yet be a problem, but at this time of the year we may get a lucky few quiet nights like this one in mid-June.

courtesy: http://thunderstorm.vaisala.com/explorer.html

If you are interested in building a system for the new (U.S.) 630m band, the CLE will give you the chance to test out your MF receiving capabilities and compare against what others in your area might be hearing.

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

Here are the full details for this weekend's co-ordinated listening event.
It is open to everyone including CLE new-comers:

Days: Friday 24 August - Monday 27 August
Times: Start and end at midday, your LOCAL time
Range: 350.0 - 369.9 kHz

This range is a busy one, usually giving us a high number of NDBs heard.

We last concentrated on these frequencies during CLE219 in May 2017.

Wherever you are, please join us and log the NDBs that you can positively
identify that are listed in this busy frequency range (it includes 350.0 kHz
but not 370 kHz) plus any UNIDs that you come across there.

Send your CLE log to the List, preferably as a plain text email
(not in an attachment) with "CLE235 - FINAL Logs" at the start of its
subject line.

Please show on EVERY LINE of your log:

# The date ( e.g. 2018-08-24  or just the day no. 24 ) and UTC
(the day changes at 00:00 UTC).
# kHz (the beacon's nominal published frequency, if you know it)
# The Call Ident.

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

If you send any incomplete logs to the List during the event, please also
send your 'FINAL', complete one.

Please always make your log interesting to everyone by showing your
own location and brief details of the receiver and aerial(s), etc., that
you were using.

We will send the usual 'Any More Logs?' email so that you can check that your log has been found OK.


You can check on all CLE-related information from the CLE Page

http://www.ndblist.info/cle.htm

It includes a link to seeklists for the Event from the Rxx Database.

Good listening
Brian
----------------------------------------------------------
From: Brian Keyte G3SIA ndbcle'at'gmail.com
Location: Surrey, SE England (CLE coordinator)
----------------------------------------------------------

(REMINDER: You could use any one remote receiver for your loggings,
stating the 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). 
-------------------------------------------------------------------

This past weekend's 'Barn Door' CLE' saw a lot of participation, in spite of the mid-summer doldrums and the universal nasty lightning noise.


After reading CLE-organizer Brian Keyte's interesting posting to the ndblist, describing his homebrew single transistor regenerative receiver, I was inspired enough to dig out the soldering iron and build one for myself.

The circuit widely described as a '1AD regen' was originally designed several years ago by crystal-radio guru Mike Tuggle out in Hawaii. Mike is widely known for his exquisitely designed "Lyonodyne" DX crystal radio, which inspired an entire decade of intense DX crystal radio building activity back in the late 90's.

Mike Tuggle's 'Lyonodyne' DX Crystal Radio

His  '1 Active Device' medium-wave regen consists of a handful of simple components and a MOSFET that is up to the task. His design was, and still is, being duplicated by many throughout the NDB DX listening community.

Mike's original 1AD regen

Mike recently sent me the circuit diagram that he eventually settled with, showing two possible ways of extracting audio with the widely popular Bogen T725 output transformer.



My own version used Mike's output scheme on the right and the RF circuitry in Roelof Bakker and Steve Ratzlaff's modified version, shown below. I had to increase the tickler (feedback) winding from 4 turns to 11 turns in order to get any regeneration. With 11 turns, my regeneration kicked-in at about three-quarters from the end of the regen control. At some point in time, while testing, some of the leads from my Bogen T725 output transformer momentarily brushed against each other, smoking my FET. Upon replacing it with another BF966, the receiver was much hotter, with regeneration kicking-in very close to the start of the pot. I'm not sure if the first FET was already damaged or that there is enough variation from FET to FET (of the same type) to make some have more gain than others. Accidentally blowing up the FET proved beneficial in the end!



Although most users employ sensitive sound powered headphones with their regens, including myself, some use modern phones with an extra stage of audio, such as an LM386.

Although not nearly as pretty as Mike's regen, my own 1AD was built in an afternoon, just for the recent Barn Door CLE.

My own MW 1AD regen

I later added a calibrated dial plate, breaking the segment from 200kHz to 550kHz into two separate bands, with calibration ~ +/- 1kHz so that I pretty much new where I was tuning at all times. This allowed me to target specific beacons and wait for them to fade up.

When first published, Mike suggested the BF966 MOSFET seemed to work well and I purchased five of them with the intention of someday building a 1AD for the NDB band. The purchase came in handy, as today, the BF966 is no longer available. Apparently the similar, and still available BF998 works well (from tests done by Steve Ratzlaff) but is now in an SMD package at just 18 cents! No doubt there are dozens of MOSFETS that will do the job and at these prices, experimenting with various devices would be a very worthwhile project.

When operating, the regen proved to be surprisingly sensitive, and by using my 10' x 20' loop, I was able to put my local pest (AP-378 kHz and 1/2 mile away) into a deep null so that its huge signal was no longer blocking the top half of the NDB band. The null allowed me to hear beacons within a few kHz of the blowtorch signal as shown below:

This coming weekend will see the 'Barn Door' CLE, mentioned in a previous blogspot here. Listeners are required to challenge themselves by listening on a receiver using a wide enough bandwidth that several kHz worth of signals can be heard at once.




The 'immersive' effect this wider bandwidth mode provides is much different than when listening with narrow filters and can make digging out IDs a lot more challenging. Throwing in some mid-summer lightning noise makes it even tougher, but if it were easy, it just wouldn't be much fun!

Many, including myself, will be using homebrew single MOSFET regenerative receivers, often called a '1AD' since they normally use just one active device. I've just finished testing my own version and have been able to hear some night time DX so hopefully the band will be quiet enough to hear some signals during the CLE.

From CLE organizer Brian Keyte, here are the details explained ... and good luck to all participants!

Hi all

It is an opportunity to bring back to life basic kinds of receiver - anything with low selectivity which allows you to hear NDBs on several frequencies simultaneously - leaving the barn door wide open!

Listening with 'back to basics' equipment often gives very satisfying and unexpected results.  It can also show us ways of improving our listening when operating more normally.

Our last Barn Door CLE was No. 209 in July two years ago.

Here comes our fifth 'Barn Door' CLE.  Between us there will be a great variety of different receiver types in use.

    Days:      Friday 27 to Monday 30 July 2018
    Times:    Start at  ## 11 a.m. on Friday 27th, your LOCAL time
                   End at   ## 3 p.m. on Monday 30th, your LOCAL time
    Frequencies:   Centred on 360 kHz (see below)
    NDBs:     NOT MORE than 100 'normal' NDBs including any UNIDs
                   (That is not intended to be a target to reach)

We are all asked to listen with NON-SELECTIVE receivers - i.e. with a WIDE
filter or NO filter.  Your 'barn door' should be open wide so you could
hear, at the same time, any NDBs 2 kHz away on both sides of your receiver
setting - E.g. NDBs on 348, 349, 350, 351 and 352 kHz with the receiver set
to 350 kHz.

## The extra daytime hours on the first and the last day might help some of
us planning to listen out of doors.

You could listen with:

1. A simple home-made receiver, such as a single transistor set with regen.
    (e.g. based on the sets used by Mike, Finbar and others).

2. OR - an Ultralight receiver, maybe one converted to cover the NDB
    frequencies with a modified aerial.

3. OR - an 'antique' receiver (e.g. Eddystone, R1155, Scott, etc.)
    Perhaps you have something you've not switched on for many years?

4. OR - a normal receiver but with NO filtering, or using a WIDE FILTER,
    (not less than about 2 kHz and no selection of an audio filter).

You choose how wide a RANGE of frequencies you will listen in, CENTRED ON
360 kHz.  You could choose 350-370 kHz or 330-390 kHz or 260-460 kHz, etc.
   (This allows each of us to choose a +/- range with enough NDBs to
   match our equipment's capability.  It will also allow our loggings to
   be compared in the Combined Results, at least around 360 kHz).

Logs should show NOT MORE THAN 100 NDBs please (if more than 100, the
harvester program will 'drop' the loggings furthest from 360 kHz).

There are several extra targets you could set yourself - maybe the wide
bandwidth, the centre frequency of 360 kHz and the 100 loggings limit do not
challenge you enough!

You could listen only in daytime and/or away from home.
Or how about NDBs on 360 +/- 10 kHz or even +/- 5 kHz?
The Twente remote receiver in Holland could be interesting to use for the
whole of your (only) CLE log.
( Go to http://websdr.ewi.utwente.nl:8901/ and read the advice there:Select AM and 'MAX IN', enter e.g. 354.7 in the frequency box and change the
filter's limits to 2 or 3 kHz from the centre frequency on both sides )

We’ll summarise everyone's equipment on the first page of the combined
results, so please describe:
The RECEIVER/AERIAL you used and the FILTER(s) selected, if any.
If homebrew, please quote:  the total number of active devices used –  e.g.
1 for a single transistor stage ( 1AD ) -  the transistor/valve types,
whether using regen.,  etc.

All the usual procedures for making logs apply:

Send your CLE log to NDB List, if possible as a plain text email and not in
an attachment.

Please show on EVERY LINE of your log:
    # The full date (or Day No.) and UTC (the day changes at 00:00 UTC).
    # kHz - the beacon's nominal published frequency, if known.
    # The Call Ident.

Show those main items FIRST on each line, before other optional details
such as Location, Distance, etc.  Please send your complete log with
CLE234 and FINAL  in the Subject line.

Whether you are a first time CLE-er or a regular, make your log interesting
to everyone by showing your own location and your equipment details.
Do feel free to share any comments you have on this unusual event.

Joachim or I will send the usual 'Any More Logs?' email at about 17:00 UTC
on Tuesday 31st so that you can check that your log has been found OK.
Make sure your log has arrived on the List at the very latest by 08:00 UTC
on Wednesday 1 August.   We hope to complete making the combined
results a day or so later.

However you choose to take part, we hope you will find your 'back to basics'
listening enjoyable and worthwhile.


P.S.   NOT FOR YOU?

Listening without narrow filters is not going to revolutionise our hobby!
But there ARE some unexpected benefits and advantages:

1. Hearing several beacons on a few adjacent frequencies at the same time
becomes easier as you get practice at recognising them by listening to their
very different audio tones. At first, when listening to a random frequency
setting, you may hear just one or two beacons. But after listening for a
little while you realise that there are three - - four, maybe more, all of
them audible without altering any of the receiver controls.
It is a skill that gives satisfaction as you improve.

2. Hearing multiple beacons like that can be useful because, with no extra
tools, you can hear NDBs over a wide frequency range much more quickly than
usual, perhaps spotting the arrival of new UNIDs or the return of occasional
beacons.  (To protect your hearing, keep your receiver gain controls fairly
low, except on very quiet frequencies).

3. With normal listening it is easy to miss any NDBs that have abnormal
carrier frequencies or non-standard offsets.  With 'Barn Door' listening
they won't escape because everything is let through.

4. When using a wide filter, you may be surprised by hearing some Broadcast
Station signals (e.g. harmonics) among the NDBs and you will be able to
identify them.
With a narrow filter, often you may not recognise an AM signal as audio
- it just sounds like nondescript 'hash' affecting a wide range of
frequencies around the central carrier.


Maybe listeners will report some other good things about their barn door
listening during the CLE - and probably some bad things too!

Do join in if you can.

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

Don't forget that help and chat regarding NDB DXing can be had on the ndb group list here.