# Low Frequency Communications



## Ancient-Mariner (Mar 30, 2009)

Although not used by me when I was at sea as a R/O 1977-1997 other than for the odd weather broadcast on CW, I am aware that some coast stations had previously used LF for traffic. Looking at some Area Scheme (before my time) do***ents, I see that Portishead had GKU on 129.95 kHz, Mauritius GZC 123.0 kHz, Ceylon GZH 123.0 kHz, Sydney VIX 44.0 kHz and Singapore GYS 112.85 kHz. 

Also from elsewhere, Madras VWM158.0 kHz, Karachi ASK 194 kHz.

North American stations also had an allocated LF frequncy.

So my question is whilst for blind or broadcast transmissions a coast station could use LF for transmission, did any coast stations listen on LF or to put it another way, did any merchant ships have LF transmission facilities? If so, was there a calling frequncy etc? I'm thinking similar to MF where for worldwide use there were only 7MF frequncies (and those including 410, 500 and 512).

Admittedly not too easy to get an effective LF transmitter aerial on a ship.

Thanks

Clive


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## King Ratt (Aug 23, 2005)

I was told at Leith Nautical College circa 1960 that some Cunarders had LF. The calling freq was 143 Khz.


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## dbayman (Jan 29, 2012)

R651400 said:


> 143 kc/s was the LW calling frequency. Portishead GKU replied on 129.95 kc/s.
> I think the big Cunarders were probably the last to use LW but Area 1a LW broadcasts from GKU continued well into the mid 60's and possibly longer.
> As for LW aerials, conventional fore and aft masted cargo ships of the time managed using a L configuration. Liners the size of the Queens I imagine had little or no problem.


I was at sea 61-67 and only GRL and GKA were used for area 1A then. GBR was still transmitting on ULF.


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## sparks69 (Dec 18, 2005)

Those were the days !


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## Ron Stringer (Mar 15, 2005)

R651400 said:


> Attachment shows GKU as part of the Area 1A bcast certainly up to 1964.


But the footnote to GKU* says that GKU was in abeyance until certain conditions applied, so it man not have been in use. GRL certainly was used for broadcasts at that time.


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## chadburn (Jun 2, 2008)

If I remember correctly the RN's Forrest Moor was using ULF.


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## dbayman (Jan 29, 2012)

R651400 said:


> Before your time GRL was until the mid fifties Burnham on Sea Radio on 500 kc/s MF. Station was part of GKA Highbridge and aerials were located at Burnham-on-Sea.
> Attachment shows GKU as part of the Area 1A bcast certainly up to 1964.


OK - it probably was still part of the 1A system but I never recall GBMS ever being invoked - so I probably never heard it - I do remember MBMS, once, during the Cuban crisis but I was in 1C at the time. 

I do remember being told at college that Ifracombe replaced Burnam for MF working


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## Troppo (Feb 18, 2010)

The VIX 44 kHz tx was actually in a northern suburb of Canberra (the capital city).

It was owned by the navy. It ceased about 10 yrs ago.

You could walk around inside the PA....

Most impressive...


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## Troppo (Feb 18, 2010)

I also see that amateurs have now got 472-479 kHz with EIRP of 5 W.

Will be interesting to see what kind of DX is achievable from a suburban backyard.

Mind you, rx performance and weak signal modes have improved a lot in the last few years.

476 kHz was the working freq of VIS.


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## Roger Bentley (Nov 15, 2005)

*LF in 1951*

I was 3rd RO on the Cheshire GLXV, she had been an AMC in WW2 we had a 1500k/W TX MW Marconi 386A and also had ability to use 143Kc/s and a couple of working freqs. On the 12 - 4 one night in the Med I called Portishead and cleared a couple of messages. Don't think the Chief RO was amused when I told him! For myself I was a bit worried when Portishead answered so quickly. Cheers, Roger


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## RayL (Apr 16, 2008)

Circa 1965, if your vessel was in, say, the Indian Ocean and the Captain wished to hold a commercially sensitive conversation with the shipowners via telephony, the R/O would contact Portishead and an arrangement would be made for a LF telephony call to take place at a certain time a few hours hence. For a successful call, it was necessary to supply an extremely accurate forecast for the ship's position, and failure would result if this were more than about 3 miles adrift. This was because Rugby Radio's LF aerials were so arranged that they could be configured to produce an extremely fine ground-wave beam capable of reaching that precise spot on the Earth's surface. To ensure privacy, the call was scrambled.


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## Ron Stringer (Mar 15, 2005)

RayL,

I think that you have turned over several pages of your calendar. It was 1st January, not 1st April. [=P]


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## RayL (Apr 16, 2008)

Please enlighten me then, Ron. The description I have given reflects what I understood at the time, but it was my first trip, and on the few occasions when telephony was used I was always a spectator.


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## King Ratt (Aug 23, 2005)

Mid 1960s to set up an R/T call from Indian Ocean or Malacca Straits or even East of that required sending an Atel msg to GKA. They alerted Rugby to the ship's QTH and required time for QSO. This was still using DSB emission from the ship TX. I recall the shoreside operator was addressed as "Tech". All in all a laborious way of making what became a link call.


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## Ron Stringer (Mar 15, 2005)

RayL said:


> Please enlighten me then, Ron. The description I have given reflects what I understood at the time, but it was my first trip, and on the few occasions when telephony was used I was always a spectator.


Sorry, I thought you were on a wind-up.

LF frequencies, when and where provided on ships, were used for telegraphy only and not for R/T. In 1965 radiotelephone (R/T) calls from the Indian Ocean would have followed the set-up procedures that you outline but all voice communication would have taken place on HF and not LF. Most HF R/T calls were still using DSB at that time although the transition to SSB was well under way.

Directional antennas were indeed used at the coast station but, regrettably, they could not target a ship at such range with an accuracy of 3 miles. Not at HF, never mind at LF, where the wavelength at 143 KHz is around 1.5 miles. To create an antenna array which could produce such a narrow beam at LF would probably require an area the size of the UK, never mind Rugby.


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## Ron Stringer (Mar 15, 2005)

King Ratt said:


> Mid 1960s to set up an R/T call from Indian Ocean or Malacca Straits or even East of that required sending an Atel msg to GKA. They alerted Rugby to the ship's QTH and required time for QSO. This was still using DSB emission from the ship TX. I recall the shoreside operator was addressed as "Tech".....


...and if I remember correctly, the radio end was addressed by her/him as 'Traffic'. As you say, a very long-winded effort, the setting up of which originally required the ship to give not less than 24 hours' notice. Each request was granted a 30-minute slot so there could only be 2 ships per hour, even if the calls were short and completed within 10 minutes. On one new ship with lots of engine room automation and cargo-handling problems, we often had to wait several hours and were occasionally told that all call-slots had been booked for the following day and made to wait more than 24 hours for the next vacant slot do that we could call the equipment makers or the shipowners. 

That at a time when other countries' coast stations were offering on-demand R/T connections which were connected directly into the shore telephone network by the coast station operator. The GPO was never famous for innovation where maritime matters were concerned. (And some shipowners would not pay the extra landline charges involved in routing calls via a foreign coast station so insisted on using Portishead - but that is another story).


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## RayL (Apr 16, 2008)

Thanks chaps. Long ago, I must have jumped to the false conclusion that Rugby was nothing but LF. It was of course famous for its time signal.

This little dialogue has been a good example of the value of Ships Nostalgia, setting me straight after decades of misunderstanding; and in the process we have also described for posterity yet another little corner of the old job.


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## King Ratt (Aug 23, 2005)

For R651400.
Info gleaned from Handbook for Marine Radio Comms.
Forms of amplitude modulation:
A Double Sideband Full carrier A3
Double Sideband Reduced carrier A3E
H Single Sideband Full Carrier H3E ( for 2182 Khz only)
J Single Sideband Suppressed carrier J3E


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## Ron Stringer (Mar 15, 2005)

R651400 said:


> Old hat really KR.
> Prior to that it was CW A1. MCW A2 and AM A3. GND GPK and all other UK coast station RT circa 1965 were A3 or AM.
> DSB Double Sideband is not a phone category unless you mention what type of carrier full (unsupressed) or reduced (supressed).


Depends on the level of nit-picking you wish to apply. DSB unsuppressed or DSB suppressed are not definitive categories either unless you specify the bandwidths employed.

Rather than fully define the method of modulation to the nth degree, we used to refer to a ship as having a DSB transmitter or an SSB transmitter. Note that modulation types A1/A2/A3 were superseded by A1A, A2H, A3H/A3A/A3J, which were themselves superseded by another nomenclature e.g. H3E, A3E and J3E. 

When speccing a transmission on a circuit it was usual to quote the modes of transmission, including the modulation bandwidth employed but in conversation I never heard anyone speak of going down to Brigham & Cowan's to fix a J3E transmitter. (Jester)


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## david.hopcroft (Jun 29, 2005)

The thumbnail was the standard GPO MF WT & RT Coast Station Transmitter during the 60's. It was called the W5, and designed by an an in-house engineer called John Denham. We had serial nrs 2 and 5 at GKZ. It was WT A1 and RT A3. There was a control cabinet (not shown) on the right. Frequency and mode changing were via huge Geipel relays. The PA valves just about visible were about 18 inches tall (I still have one on each type, real conversation pieces. CV1647 and CV1650 come to mind. Beamed Tetrodes also rings a bell, made to order by Plessy at Paignton). Working MF RT only coasters into the Western Med at night was no problem. We did have Rx aerial filters on working channels, but no directional arrays.

Going back to GRL - I found it indispensible when doing a stint on an MF only coaster (T10A), especially as the frequency was on the MF half of the G12/13 receiver !

David
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## david.hopcroft (Jun 29, 2005)

Yes, sorry, A2, MCW was the norm, but the A1 option was available. The first thumbnail show the control panel with the button options MCW, RT, CW, LP & HP selectable. They were repeated at the Ops consols. The other thumbnail is the whole thing - all 12 feet of it about 6 foot high !

David
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## Graham P Powell (Jun 2, 2007)

Very interesting pictures David. Of course at GKA we never saw our
transmitters!. I worked as a telephone engineer before transferring to GKA and the old Post Office had some seriously good engineers.
Mr Denham was obviously one of them.
rgds
Graham Powell


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## david.hopcroft (Jun 29, 2005)

Yes, this is the in-house receiver - before the MIMCO Mercury's. W4 comes to mind, but not sure. They were still in use May 1968 when I arrived at GKZ. In fact, they went on until the EC958's came.

My thumbnail is GKZ 1947. One on each WT (top) and RT (foreground).Not very visible to the left of the Op on WT is the DF control. This was a boon in the 50's and early 60's as WT traffic from coastal colliers etc was plentiful, so the DF receiver was used to shut out most of the QRM on working frequencies. 

David

ps. I know it was 1947 as the Op on WT told me much later. Does anyone recognise him as John Handford ??

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## david.hopcroft (Jun 29, 2005)

I will see if there are any left at Rugby who remembers that far back !!

The W5 didn't come along until the early fifties. John told me that when the photo was taken in 1947, they were still using the original 1927 1.5kw transmitter. It was getting very long in the tooth by then and John said you often had to go inside the cage and give it a bash to change frequency !!.

The W5 was though a tough old beast. This thumbnail is February 1953, with the tide mark still showing. It was dried out, cleaned up and brought back to life. Doubt that would be the case these days !!

David
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## G4UMW (May 30, 2007)

My copy of "Watchers of the Waves" has a photo of the operating consoles at GKR in the 1950s; the in-house receiver is visible and is described as a Post Office W20 D/F receiver.


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## david.hopcroft (Jun 29, 2005)

W20 sounds about right. The 'W' perhaps means simply 'wireless' equipment type since the GPO was all encompassing at that time.

This is also in Brian's book - shows the W20 at the Festival of Britain exhibition in 1951.

You would think we could remember these things quite well all the time we spent sat in front of them !!

David
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## david.hopcroft (Jun 29, 2005)

The x in question is definitely W20, but can't find out much more. I think it may even have been a Plessy design built to spec.

I was sent this from Rugby. It is a WT point somewhere - morse key but no telephone dial - but I can't recognise where. Not GKZ.

David
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It came to me as a PDF, so hope you will see it OK.


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## hawkey01 (Mar 15, 2006)

David,

a good sea view from the windows and looks like land in the far background. Cannot think of a c/station that had that kind of view. Appears to be very close to the water. Could it be Oban/Wick? Although most had sea views but not so close.


Hawkey01


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## GBXZ (Nov 4, 2008)

No radio room clock but there is an ashtray ! Could the console 
be a trial or new design being tested ?
Rgds


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## david.hopcroft (Jun 29, 2005)

I had not thought of pre-STD, so yes it is an RT/WT consol. Direct trunk access to the local exchange. When I arrived at GKZ in early '68, there were primitive call timers fed by a 6-second timing pulse derived from an electro-mechanical clock in the Landline Room. They didn't seem to work half the time, so we had stop watches like the one shown. The RT mike was in use still in 1968.

I think it is a grass field outside, and looks very like an 'opening day' photograph to me. 

David
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## holland25 (Nov 21, 2007)

I have had a look through Watchers of the Waves and there is a picture of Wick Radio.pp 98. The windows,the clock and the calendar look similar and through the window you can make out the wall. You can also see a console up against the right hand window which is slightly open in both pictures. There is also a black box of some kind to the left of the far console. The date on the calendar would appear to be the same. Just some observations.


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## david.hopcroft (Jun 29, 2005)

One of the Rugby engineers thinks the W20 is a Redifon Rx. - post #40

David
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## david.hopcroft (Jun 29, 2005)

The W20 on the consol at #40 is Consol 7 at Wick with the receive aerial amplifier against the wall. 

David
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## ernhelenbarrett (Sep 7, 2006)

Didnt the two Original Queens, Mary and Elizabeth communicate to each other
on either 123Khz or 132 Khz, also think they could QSO GLD on one of those frequencies too.
When I worked at VIS we did the Area 7 Broadcasts using the VIX freq of 44Khz up to VIX7 during the day.
Ern Barrett


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## GW3OQK (Jun 10, 2010)

I've had a QSO on 472.8. (Swansea to Bristol) Not much CW activity. On MF again after 40 odd years. I'm using a T1154 from 1943. Anybody got an Oceanspan on air?
Andrew
GW3OQK


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## charles henry (May 18, 2008)

Ancient-Mariner said:


> Although not used by me when I was at sea as a R/O 1977-1997 other than for the odd weather broadcast on CW, I am aware that some coast stations had previously used LF for traffic.
> Admittedly not too easy to get an effective LF transmitter aerial on a ship.
> 
> Thanks
> ...


Antennas are the major problem. I once had to put an LF teletype link between Fort Churchill and Coral harbour. Coral harbour was transmitting one kwatt at 104khz.
I eventually put in a Beverage antenna 15 miles long........ and 10 feet above ground. 
Ah...... memories

Chas (Pint)(Pint)


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