In our final NDB DXing outing for this year, Robert Connolly investigates Fishnet, Channel Marker and Cluster Beacons, evaluates Mini-Whip aerials, prepares for Winter DXing and offers his loggings.

 

Generally, the non-directional beacons I refer to in this column are those used by aviation. There are also the few remaining marine NDBs, along with former marine NDBs that are now used to transmit DGPS signals.

However, there are also some other non-directional beacons, which monitors come across from time to time. These may be heard on MF and HF frequencies. These are used by fishing industries in many parts of the world and are referred to as ‘Driftnet Beacons’, although the use of driftnets is now restricted.

Nevertheless, these transmitters are still used by long-line fishing vessels and may also be referred to as ‘fishnet beacons’. It is thanks to reader Kevin, who recently emailed me regarding these, that I remembered that this was an area I had not looked at for some considerable time.

These lines may run for many kilometres and can have secondary lines branching off them using thousands of baited hooks. They are deployed by the fishing vessel and left for a period of time before the vessel returns to haul the line back on board with the catch.

Driftnet beacons are radio beacons deployed in the sea by commercial fishermen using these long lines. The beacons enable them to easily locate their lines for retrieval, and they operate in just the same fashion as a normal marine NDB. The transmitter unit is a compact, waterproof, and battery powered, device of just under a metre in height, with a 0.2m aerial deployed at one end of the long line and floating on top of the water.

The normal battery life is around 500 hours, and the image in Fig. 1 shows an example of a fishnet beacon.

Fishnet beacons operate on frequencies between 1.6 and 28.5MHz, although operation between 1.6 and 4 MHz is most common. Their transmission mode is A1A (Morse code) with a power of either 4 or 10W. This provides a practical working range of up to 200km.

Their identification signal consists of a combination of letters and numbers: Two letters and one number for Class 3a; two letters and two number for Class 4a; one number and three letters for Class 4b; two letters and three numbers for Class 5a; and one number and four letters for Class 5b.

The ident is transmitted three times over the period of one minute, followed by a silence period of three minutes, and then the cycle begins again. Although their official range is 200km, they can often be received over much greater distances.

While I am not aware of any official registry for these beacons, some amateur loggings may be found at the following websites:

www.qsl.net/n2sln/driftnetbeacons.htm

www.hfunderground.com/wiki/Fishnet_beacon

www.genesisradio.com.au/VK2DX/fishnet.html

Given the fact that these beacons are used in a maritime environment, it is not possible to establish their location, or, for that matter, their country of operation. Countries that use them include North and South America (Atlantic, Arctic and Pacific waters), Asia, Australia and New Zealand. I am also led to believe that some are used by Norway and Russia in the Arctic region.

Many of these beacons operate continuously when deployed, but there are some that only operate when activated by a Selcall transmission from the vessel, using the buoy. Their general specification and service range is the same as the others, but they are fitted with a Selcall receiver that operates on either 2331.5 or 1902.5 kHz. In addition, the battery of the beacon will last for up to ten times longer.

Amateur DXers know that locating an MF/HF transmitter and aerial on saltwater increases its receivable range by up to ten times, possibly even more during darkness; hence the reason why these are received by amateurs from long distances away.

 

Channel Markers and Cluster Beacons

There are other types of beacon that is commonly receivable in various parts of the world, including the British Isles and Europe. These normally take the form of transmitting a single letter, and some will occasionally break into fairly high-speed Morse code transmissions.

The two main types of these are referred to as channel markers and cluster beacons. Like fishnet beacons, they can be heard on a number of MF and HF frequencies. It is believed that they are operated by the Russian Military, mainly the Navy, and that the letters refer to their various bases. Their exact function is not known, and it is probable that they are being used to ensure nobody else can use those frequencies, leaving them clear for when the Russian Military wishes to send operational signals.

They are possibly also used as propagation beacons to allow Russian naval vessels to select the optimal frequency for operational communications, given their current location and prevailing propagation conditions.

Channel markers only transmit one letter constantly, while cluster beacons will transmit several letters constantly and all within a few Hz of each other.

Table 1 details the suspected locations of the letters used by channel marker beacons and the frequencies used by cluster beacon stations.

 

Mini-Whip Aerials

September’s Storm Ali hit hard here, and I am considering replacing my damaged Datong AD 370 active aerial with a mini-whip alternative (see my report in this month’s Maritime Matters).

So, what exactly is a mini-whip active aerial? Most current mini-whips are based on a design by Roelof Bakker PA0RDT, for low-frequency reception in a city environment and for use in small gardens.

Following tests using an active whip aerial, designed by G4COL, it became clear that, at LF, an active whip is a capacitance, coupled to the electric field, and that the whip length could be reduced from 100 to 30 cm without loss of performance; the shape becomes irrelevant, if the required capacitance is available.

In practice, the ‘whip’ can be, for instance, a small piece of copper-clad, printed, circuit board. A small die-cast aluminium box can also be used, with the buffer amplifier mounted inside.

Tests were performed to find the optimum dimension for what became the PA0RDT-Mini-Whip. To prevent receiver overload, the maximum output has been set to about - 20dBm. The buffer amplifier has been optimised for good strong-signal-handling performance.

Unfortunately, these days, my eyesight is not just the best for close-soldering work, especially with surface- mount components, so I decided that I would purchase one that had the circuitry already built, leaving me with minimal work to complete the connections and secure them in a suitable casing.

There are a number of ready-made mini-whip aerials available for sale on eBay, with most seeming to come from Russia or Ukraine. For various reasons, I preferred to purchase from either the UK or Europe.

I came across a UK-based supplier who sells an IP 33 Mini-Whip Active Aerial, which may be purchased as a kit, with all the components to be soldered onto the circuit boards, or already assembled, with just the final exterior connections (power supply, two SMA sockets on the power board for coaxial cable connection, along with a female BNC connector that should be soldered to the mini-whip board) to be carried out for just a few pounds more. I opted for the assembled version (Fig. 2).

The aerial board is 110x30mm and is supplied with a 40 x 10mm power interface board that connects the aerial to the receiver. The 12V DC power is conducted from this board to the mini-whip board, via the coaxial cable. Complete assembly instructions can be downloaded from this website:

https://tinyurl.com/ASSEMBLEDMiniWhip

The UK seller, Mike, provides support here:

[email protected]

General specifications for the IP33 Mini-Whip are as follows: frequency range: 10kHz-30MHz; power: 12-15V at 38 mA; second order output intercept point: > + 74 dBm.; third order output intercept point: > + 33 dBm; dimensions: length: 110mm, diameter: 33mm. The feed line is 50-100Ω coaxial cable, up to 100m.

These specifications are very similar to the original PA0RDT mini-whip, and my twenty-year-old Datong AD370 active aerial. It does not come with an enclosure, but a short length of 40mm plastic pipe fitted with end-caps will provide a suitable outdoor case.

I used a small plastic project box for the interface and a slightly larger waterproof project box for the aerial unit. It should be noted that mini-whip active aerials should be used outside and mounted as high as possible, and as far away as possible from potential sources of interference.

 

Winter DX Season

We are now into the main winter DX season, so it will be interesting to see what propagation conditions will be like over the coming months.

Rob Evans e-mailed me at the end of September to let me know that he had received 372 kHz OZN Prins Christian Sund from Greenland and also 274 kHz SAL from Cape Verde at 0500 UTC. Reception of these is always a reliable indicator of the fact that that the main NDB DS season is starting to get underway.

I received a report from a DXer in the Czech Republic who recently received the following remnants from marine NDB chains located in the Black Sea, confirming that they are still active: SW - Mys Khersonesskiy and EYa Mys Yevpatoriyskiy Light (note Ya is a Russian special Morse character .-.-), both from Ukraine on 309.5 kHz. Received on 312.5 kHz: DB Doobskiy, Black Sea Russia and AT - Mys Aytodorskiy Ukraine. There is a third NDB believed to be still active in this chain, TR Mys Tarkhankutskiy.

To stand a chance of hearing these NDBs you have to listen to the frequency carefully for at least six minutes. These marine beacon chains normally have six NDBs on the same frequency, with each allocated one minute, during which interval it would transmit three times, followed by a long tone, and then by a single identification transmission at the end of the allocated period.

Time slots for these beacons on 309.5kHz are as follows: EYa slot 1, TR slot 5 ,and SW slot 6. On 312,5kHz, it is AT using slot 1 and DB slot 4.

Until next time, good DX.

 

DXers this month’s log table:

NDB reception this period during daylight (*).

A: Rob Evans, South Wales, Icom IC-R8600 with a long wire aerial.

B: Andy Thomsett, Southwest England. Airspy HF+ or SDRplay RSPduo and a PA0RDT Mini-Whip.

C: Robert Connolly, Co. Down, Northern Ireland. NRD 525, Datong AD370 active aerial, Timewave DSP+9.

 

Table 1: Suspected locations of the letters used by Channel Marker Beacons and of the frequencies used by Cluster Beacons.

 

Channel Markers
ID Letter	Location
A	Astrakhan, Russia
C	Moscow, Russia
D	Sevastopol, Ukraine
F	Vladivostok, Russia
K	Petropavlovsk-Kamchatsky, Russia
L	Tirana, Albania (inactive)
M	Magadan, Russia
P	Kaliningrad, Russia
R	Izhevsk (Ustinov), Russia
S	Severomorsk, Russia
V	Khiva, Uzbekistan
Cluster Beacons
ID Letter	Frequencies (kHz)
D	3593.7, 4557.7, 5153.7, 7038.7, 8494.7, 10871.7, 13527.7, 16331.7, 20047.7
P	3593.8, 4557.8, 5153.8, 7038.8, 8494.8, 10871.8, 13527.8, 16331.8, 20047.8
S	3593.9, 4557.9, 5153.9, 7038.9, 8494.9, 10871.9, 13527.9, 16331.9, 20047.9
C	3594.0, 4558.0, 5154.0, 7039.0, 8495.0, 10872.0, 13528.0, 16332.0, 20048.0
A	3595.1, 4558.1, 5154.1, 7039.1, 8495.1, 10872.1, 16332.1
F	7039.2
K	5154.3, 7039.3, 8495.3
M	5154.4, 7039.4, 8495.4, 10872.4, 13528.4, 16332.4

 

Table 2: NDB Loggings (Part Four – December 2018)

 

FREQ	C/S	LOCATION	COUNTRY	DXer
274.0	SAL	Ilha Do Sal	Cape Verde	A, C
277.0	CHT	Chiltern	England	A
316.0	OE	Dublin	Republic of Ireland	B, C*
318.0	BE	Bordeaux - Mérignac	France	B
318.0	BPL	Blackpool	England	C*
319.0	VAR	Varhaug	Norway	B, C
321.0	ABY	Albert - Bray	France	B
321.0	STM	Scilly Isles	England	B, C
322.0	RL	La Rochelle	France	C
323.0	WPL	Welshpool	Wales	A
325.0	AST	Asturias	Spain	B, C
326.0	LM	Le Man - Arnage	France	B
327.0	LNZ	Linz	Austria	B
327.0	MVC	Merville - Calonne	France	B
328.0	CL	Carlisle	England	B, C*
328.0	HIG	San Sebastian	Spain	B
328.5	EGT	Londonderry	N. Ireland	B, C*
331.0	GLW	Glasgow	Scotland	C*
331.0	GST	Gloucester	England	B, A
331.5	TLF	Toulouse - Francazal	France	B
332.0	OY	Aldergrove	N. Ireland	C*
333.5	VOG	Voghera	Italy	B
334.0	GMN	Gormanstown	Republic of Ireland	B, C*
334.0	KER	Kerry - Farranfore	Republic of Ireland	B
335.0	TON	Torralba de Aragón	Spain	B
335.0	WCO	Westcott	England	B
337.0	EX	Exeter	England	A, B
337.0	MY	Myggenaes	Faeroes	B, C
337.0	WTN	Warton	England	C*
338.0	FNY	Doncaster	England	C*
338.0	GU	Brest - Guipavas	France	B, A
338.0	PST	Porto Santo	Madeira	B
339.0	BIA	Bournemouth	England	B
339.0	OL	Shannon	Republic of Ireland	B
340.0	HAW	Hawarden	Wales	B, C*
341.0	EDN	Edinburgh	Scotland	B, C
342.0	VA	Vannes	France	B
342.0	VLD	Valladolid	Spain	C
342.5	NWI	Norwich	England	B
343.0	YVL	Yeovil	England	B
345.0	CSD	Daouarat	Morocco	B
345.0	LN	Lannion	France	B
346.0	LHO	Le Havre	France	B, C
347.0	NQY	Newquay	England	C*
347.5	TD	Teesside	England	C
349.5	LPL	Liverpool	England	C*
350.0	FU	Hamburg	Germany	B
351.0	OV	Visby	Sweden	B, C
352.0	ENS	Ennis	Republic of Ireland	C
352.0	NT	Newcastle	England	C
352.0	WOD	Woodley	England	B
353.0	KIL	Kiel	Germany	B
355.0	PIK	Prestwick	Scotland	B, C*
356.0	SGO	Sagunto	Spain	B
356.0	WBA	Wolverhampton	England	B, C*
357.0	LP	Cholet	France	B
358.0	BRS	Biscarosse	France	B
358.0	LT	Le Touquet	France	B, C
359.0	LOR	Lorient	France	B, C
359.0	RWY	Ronaldsway	Isle of Man	C*
360.5	MAK	Makel	Belgium	B
361.0	CFN	Carickfinn	Republic of Ireland	B, C
363.0	PI	Poitiers	France	A, B
364.0	KNK	Connaught	Republic of Ireland	C*
364.0	PU	Pau	France	B
365.0	VR	Gran Canaria	Canaries	A
366.0	UTH	Uthaug	Norway	B
367.5	OX	Oxford	England	A, B
368.0	WTD	Waterford	Ireland	A, B, C*
368.5	WHI	Whitegate	England	B, C*
369.0	GL	Nantes - Atlantique	France	B
371.0	STR	Sintra	Portugal	C
372.0	ODR	Odderøya	Norway	C
372.0	OZN	Prins Christian Sund	Greenland	A, B, C
373.0	MP	Cherbourg - Maupertuis	France	A
374.0	BGC	Bergerac - Roumanie	France	B
376.0	BJA	Beja	Portugal	B
378.0	KLY	Killiney	Republic of Ireland	B, C*
380.0	CBL	Campbelltown	Scotland	C*
380.0	FIL	Horta	Azores	B
380.0	RQ	Quimper - Pluguffan	France	B
380.0	VNV	Villanueva	Spain	B
382.0	LAR	Arruda	Portugal	B, C
382.0	SBG	Salzburg	Austria	B
383.0	ALD	Alderney	Channel Islands	A, B
384.0	SLG	Sligo	Republic of Ireland	B, C*
385.0	WL	Walney Island	England	C*
386.0	BZ	Brize Norton	England	B
387.0	AV	Asturias	Spain	B
387.0	BGP	Brest - Guipavas	France	A, B
387.0	CML	Clonmel	Republic of Ireland	B, C*
388.5	CDF	Cardiff	Wales	A, B
389.0	CP	Lisbon	Portugal	B, C
389.0	PX	Périgueux	France	B
390.0	DR	Dinard	France	B
390.0	SO	Santiago	Spain	B
393.0	BD	Bordeaux - Mérignac	France	B
394.0	DND	Dundee	Scotland	B, C*
394.0	NV	Nevers - Fourchambault	France	B
395.0	B	Bilbao	Spain	B
395.0	FOY	Foynes	Rep. of Ireland	B, C*
395.0	LAY	Islay	Scotland	C*
397.0	OP	Dublin	Rep. of Ireland	C*
397.0	BLB	Blois - Le Breuil	France	B
397.0	FV	Fuerteventura	Canary Islands	B
397.0	ZR	Béziers - Vias	France	B
398.0	MT	St-Nazaire - Montoir	France	B
398.0	OK	Connaught	Rep. of Ireland	C*
399.0	NGY	New Galloway	Scotland	B, C*
400.0	AG	Agen	France	B
401.0	COA	La Coruña	Spain	C
401.0	LA	Laval	France	B
402.5	LBA	Leeds	England	B
404.0	AGO	Angoulême	France	B
404.0	CNE	Caen - Carpiquet	France	B
404.0	LRD	Lleida	Spain	B
406.0	BHX	Birmingham	England	B
406.5	BOT	Bottrop	Germany	B
409.0	SG	Såtenäs	Sweden	B
410.0	C	La Coruña	Spain	C
410.0	ETN	Étain	France	B
412.0	GRN	Gerona	Spain	B
413.5	DLS	Berlin - Lubars	Germany	B
414.0	BRI	Bristol	England	A, B
414.0	HD	Sandnessjøen - Hestad	Norway	B
415.0	TOE	Toulouse	France	B, C
416.0	POZ	Požarevac	Serbia	B
416.0	SA	Santander	Spain	B
417.0	AH	Ängelholm	Sweden	B
417.0	CVT	Madrid - Cuarto Vientos	Spain	B
417.0	SNO	Santiago	Spain	B, C
418.5	MT	Offshore Installation	North Sea - UK	B
419.0	EMT	Épinal	France	C
420.0	HB	Belfast City	N. Ireland	B, C*
421.0	BUR	Burnham	England	A
421.0	GE	Madrid	Spain	B, C
422.0	PAM	Pamplona	Spain	B
423.0	TS	Toulouse - Blagnac	France	B
424.0	PHG	Phalsbourg - Bourscheid	France	B
424.0	PIS	Pisarovina	Croatia	B
425.0	EVR	Évora	Portugal	B
426.0	CTS	Castets	France	B
426.0	SH	Shobden	England	A
427.0	RY	Royan	France	B
428.0	BST	Lanvéoc	France	B, C
428.0	CTX	Châteauroux	France	B
430.0	SN	Saint-Yan	France	B
431.0	SAY	Stornoway	Scotland	B
432.0	PK	Pardubice	Czech Republic	B
433.0	VON	Vigo	Portugal	B
433.0	VNS	Castor Platform	Spain (offshore)	B
433.5	HEN	Henton	England	A, B
468.0	FTZ	Fritzlar	Germany	B
488.0	ILM	Illesheim	Germany	B

 

 

This article was featured in the December 2018 issue of Radio User