Alphabetical Index

Non-directional LF Beacons

Introduction

With the RSGB discussing a possible experimental amateur allocation at the top end of long wave near 500kHz I took an opportunity during the Christmas break to take a listen to the LW band between 275 - 500kHz. I was curious to hear what’s still there these days. A week earlier I’d built a small VLF up-converter to listen out for SAQ on 17.2kHz and by increasing the cut-off frequency of the input filter I managed to bring up the sensitivity some 20-30dB in the LW band, so there was plenty of scope for LW reception with my 50 foot wire down the garden using the converter with the FT817.

LW Sensitivity

You may find that a preamp is needed on your own receiver if it covers long wave, as amateur rigs and general coverage receivers are often deaf in this part of the spectrum. Although broadcasters use many kilowatts the beacon signals are designed for relatively local reception only on approaches to airfields, so can be considerably weaker.

As a guide to sensitivity on LW (for those in the UK) there is a useful Greek data transmitter on about 138kHz that sends a carrier and, every few seconds, a burst of data. If you can hear this as S9+ you have a reasonably sensitive set-up. If this is weak then you need to try harder with your set-up.

Fewer Beacons

A lot of the LW marine beacons that used to be there seem to have disappeared since I last looked some years ago. In the age of sub £100 GPS receivers with accuracies of a few metres the sailors around the UK and Northern Europe have no need to direction-find using a couple of MCW beacons: the GPS receiver just tells them.  The MCW and CW beacons that remain appear to be linked to airfields. I also noticed several other types of long wave beacon sending data but I did not try to decode these.  I believe they now send differential GPS data to improve GPS accuracy. Without decoding the data it was not possible to identify these.

Finding Beacons

My search started by listening for a local beacon about 10 miles down the road at Cambridge Airport. This has been around for years putting out a few watts to a Marconi antenna up near the end of the runway. Sure enough it was there nice and strong on 332.5kHz sending the letters “CAM” in slow CW. A casual tune around and I had another half dozen such beacons in the log.   All were sending their callsigns in very slow modulated CW so even if your morse is not very good you should be able to quickly copy them after a few repeats.

A search for “LW NDB” on Google brought up an excellent site about beacons of all sorts http://www.beaconworld.org.uk/enter.htm. In amongst lots of useful data on this site was a full list of operational long wave beacons around the UK. Using this list as a guide (and with a cup of tea in hand!) I slowly tuned for about 45 minutes from the LF to HF end of the beacon band to see what could be identified. Many beacons were copied with the FT817 in AM mode but for some I put it into CW mode and turned on the narrow 500Hz filter. The list below shows what could be copied without too much effort in daylight on that mid-winter day. At night I expect many more would be audible. The last time I listened in this part of the spectrum many years ago it was possible to hear LW beacons from as far south as Spain and up to Norway without any real effort at night.

Among the stations identified were a few that did not appear on the UK beacons list. These may be new ones or perhaps are located outside of the UK. I am sure that, with a little patience, all of the NDBs in the UK could be copied, especially with the aid of a directional loop antenna to null out some stronger stations and allow copy of weaker ones, especially at night. 

Some listeners make an entire hobby out of beacon reception. Many beacons send QSLs in response to helpful reports (not sure about UK NDBs though) and certainly amateur HF beacon operators always appreciate such reports. 

Log of NDB Stations Received (mid-winter daylight, near Cambridge UK)

Location: Burwell, Cambs  28.12.06

 

TIME

FREQ

CALL

LOCATION

RST

1530

277.0

CHT

Chiltern

559

1531

282.0

LA      

RAF Lyneham            

559

1532

316.0

EPM              

Epsom

559

1534

322.0

LCY     

London City        

559

1536

323.0

SBL     

Sherburn-in-Elmet  

559

1540

325.0

OF      

Filton             

529

1542

332.5

CAM    

Cambridge          

599

1544

335.0

WCO   

Westcott           

559

1545

338.0

FNY

Doncaster-Sheffield

569

1547

342.5

NWI     

Norwich            

559

1548

345.0

LUT     

Luton              

569

1549

347.0

MTN     

Manston (Kent)     

579

1552

352.0

WOD   

Woodley            

569

1556

353.5

EME     

East Midlands      

559

1557

356.0

WBA     

Wolverhampton

559

1556

360.9

MAK

??

579

1558

362.5

SND    

Southend           

589

1558

363.5

CT      

Coventry           

589

1558

365.0

GY      

London Gatwick     

559

1559

371.5

NH      

Norwich            

569

1600

378.5

NN      

Northampton

579

1601

386.0

BZ      

RAF Brize Norton       

589

1601

391.5

BOU     

Bourn              

589

1613

398

ONO

??

579

1612

401.0

FNL     

Fenland            

559

1612

402.5

LBA     

Leeds Bradford    

569

1611

403.6

MRV

??

589

1609

406.0

BHX     

Birmingham         

559

1601

421.0

BUR     

Burnham            

589

1601

429.0

SSD    

Stansted           

589

1604

426.2

BST

??

549

1602

433.5

HEN

Henton

589

 Conclusions

Based on the results during my brief listen to this part of the spectrum I could imagine good inter-G coverage with relatively low power even with the inefficient antennas that we could erect in our back gardens on long wave. It should be somewhat easier to get useful results around 500kHz,than on 136kHz.

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