# Ships' working frequencies



## Worldspan (Jan 2, 2012)

Of course, all ships had 500, 512 and 410 (the latter for DF but I never used it) and I seem to remember that the working frequencies were 480, 468, 454 and 425. Are these correct?

Was it the case that a ship with, say, an Oceanspan could transmit on all of the working frequencies but was permitted to use only two? I mean were just two frequencies allocated to each ship? And if it was two, were they always paired the same … perhaps 480 and 454? Or was a ship with a transmitter that had all of the working frequencies free to choose which one was best?

Memory lapse!

Thanks in advance. W


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## Papa Bear (Apr 15, 2007)

It seems to me that, if I remember correctly I had the above MF freqs and could use whichever I desired. John L.


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## Paul Braxton (Jul 21, 2005)

Ships were fitted with all the frequencies you quote; all with dedicated crystals, in the case of the Oceanspan transmitter, say, until the later transmitters with synthesised drives came along. That gave you a bit of leeway. If you were working Nitonradio/GNI, for instance, you would probably go for 468, his working frequency being 464, or Landsendradio/GLD, who was on 438 and would often use 425 from the ship. It got a bit congested in European waters (Scheveningen/PCH was on 461, so you would use 468 or maybe 454 with him. Hopefully the relative distances between stations would lessen problems with interference). That's how I used to work, anyway. Somehow it worked out alright.


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## Wismajorvik (Dec 29, 2011)

Worldspan said:


> Of course, all ships had 500, 512 and 410 (the latter for DF but I never used it) and I seem to remember that the working frequencies were 480, 468, 454 and 425. Are these correct?
> 
> Was it the case that a ship with, say, an Oceanspan could transmit on all of the working frequencies but was permitted to use only two? I mean were just two frequencies allocated to each ship? And if it was two, were they always paired the same … perhaps 480 and 454? Or was a ship with a transmitter that had all of the working frequencies free to choose which one was best?
> 
> ...


In the early sixties vessels I sailed on had only two working MF frequencies. On one vessel the transmitter had selectable LC oscillators as a back up to the crystals but unfortunately the inspector discovered that these had been retuned to the ‘missing’ working frequencies and adjusted them back to the original frequencies. The limit of two frequencies was frustrating as often a coast station after a traffic list would advise listening to a specific frequency, which you may not have,


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## Ron Stringer (Mar 15, 2005)

In the UK a ship was only licensed by the GPO to use two of those four available MF working frequencies. This was supposedly to ensure that there was a distribution of traffic on any particular working frequency but I fail to remember the reasoning behind this.

Of course many ships were able to use all the working frequencies but such use was outside the terms of the ship's radio licence. Some GPO surveyors were keen to insist that crystals for unlicensed frequencies were removed (this was even more stringently applied to the MF R/T frequencies, especially on fishing vessels) but most paid little attention.

The this caused a problem for ships spending time on the US Coast, where 448 kHz was a commonly requested/demanded working frequency by coast stations. Most such vessels carried a crystal for 448 kHz, either installed in the transmitter or secreted in a drawer.


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## Tony Selman (Mar 8, 2006)

That's interesting Ron on two fronts. All the ships I sailed on had all the crystals installed and I can never remember a surveyor saying I should use only two. To be honest that is the first time I can recall hearing that. I spent a lot of time on the US Coast over the years and can never recall using 448 or being requested to. At this distance I can't ever remember as ship having the 448 crystal secreted in a drawer. What years was this relevant?


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## Ron Stringer (Mar 15, 2005)

Tony,

The 448 experiences were 1960s during which time I sailed on/near the US on 4 ships where US stations (especially USCG stations accepting OBS and AMVER messages) regularly directed me to 448 kHz. Which none of the ships carried. 

Whether or not shipowners could obtain permission to use additional frequencies on application to the GPO I don't know, but I suspect that was the case, since I sailed on and visited ships with a full frequency complement. However the norm was for only two of the four to be assigned by the GPO's licensing branch. The notices of allocation were processed by a section of the MIMCo supplies department which ordered up the appropriate crystals and delivered them to the shipyard where the transmitter was to be fitted.

The checking of fitted Vs licensed frequencies was also 1960s and precautions against any such problems used to be part of a shore technician's pre-survey checks prior to a visit from the GPO Radio Surveyor. On the South side of the Tyne, only one of the two regular surveyors had this particular bee in his bonnet but normally we didn't know until the last minute which one would be turning up to do the survey.

Later, whilst working at the Chelmsford office I saw reports of similar problems at other ports. Fortunately transmitter design evolved to a state where it was not potato limit the working frequencies and the problem went away.


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## Varley (Oct 1, 2006)

I know there were a lot of Irish in Macaroni Ron but I didn't realise Chelmsford had had to impose a potato limit.

(Weren't the allocated frequencies licensed according to whether you were a high traffic ship or not?)


(Did you know you can tell the polarity of a DC supply with a potato?)


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## jimg0nxx (Sep 1, 2005)

When I started in 1962 using the old Oceanspan with a variable LC oscillator you could tune any MF frequency desired. On joining a ship so fitted I would note the readings on said oscillator and avail myself of all working frequencies(illegal of course). Never had any comeback. On passenger vessels I sailed on fitted with Globespan all working frequency crystals were available.


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## david.hopcroft (Jun 29, 2005)

In the early 60's, my main MF Tx was a T10A, and I really can't remember how many it had. Later whilst at GKZ our working frequency was 484. I never directed anyone, but the vast majority opted for 480, especially the ubiquitous Russians with OBS messages.

David
+


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## majoco (Oct 15, 2008)

If I recall, the "Sir William Walker" Stevie Clark's collier only had 425 and 468 KHz as working frequencies but as time actually at sea was limited to the Tyne to Shoreham and back again so it was fairly rare to actually send any real messages other than a T/R - VHF and MF telephone calls were made frequently. Blue water ships had a full complement of crystals and some oddball spares too.


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## Worldspan (Jan 2, 2012)

Thanks for all the interesting replies. I do believe that on 'Orontes' we were limited to two working frequencies although I can't remember what they were.

But on this matter, were such working frequencies always issued as, say, 480 and 425? I mean were they always paired in the same way? I confess that I'd never heard of 448 as a working frequency.

W


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## Wismajorvik (Dec 29, 2011)

On a number of vessels it was possible to increase the signal level to the receiver by adjusting the tuning on the powered off transmitter. This was useful when attempting to copy wx or tfc list from a distant mf cs. The larger transmit aerial coupling signal into the rx aerial. Therefore it would be beneficial to use a working frequency close to the cs frequency, (if you had one).
Off topic, on my first ship the hf tx was only equipped with 6,8,12 and 16Mhz.


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## Ron Stringer (Mar 15, 2005)

Worldspan said:


> I confess that I'd never heard of 448 as a working frequency. W


448 kHz as a working frequency for ships was only available for use in Region 2 (North and South America) as set out in ITU Radio Regs, not in other Regions - another potential source of conflict at GPO inspections. I suspect that allocation might have been because it had been in common use by US ships when the Radio Regs were amended to define the Maritime Mobile frequency band and its uses. Such anomalies are not uncommon in the Regs when proposed international changes conflicted with existing uses in a major member state and a deal was done to get round the problem. 

A similar example was the designation and use in the USA of some of the two-frequency maritime VHF channels. There, only the lower frequency of the pair was made available for marine use, the higher frequency having been allocated to railways prior to ITU setting out the international frequency plan in Appendix 18 to the Radio Regs. This meant that certain of the VHF channels above Channel 16 were not available to most ships in US waters but were commonly used by local ships and coast stations.


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## Tony Selman (Mar 8, 2006)

I spent a fair bit of time regrettably pounding across the North Atlantic on the Cunard cargo ships. If anyone was going to be allocated 448 it would have been them. To the very best of my knowledge with a gap of over 50 years I do not recall either the frequency being allocated or me ever using it. I will though ask a couple of R/Os who were on the run and they might refresh the little grey cells. One, almost unbelievably, spent nearly his while life on the North Atlantic so I am sure he will know.


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## R651400 (Jun 18, 2005)

The only time I came across 448 as a MF working frequency was on a WW2 US built US liberty and later two post WW2 US built Niarchos tankers which makes me think it could have originally been a FCC/North American frequency allocation. 
Never came across it on any UK/European build.


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## david.hopcroft (Jun 29, 2005)

Ref #13 

Wismajorvik..

Was it one of these ……... Seimens SB186 ?

David
+


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## cajef (Feb 8, 2012)

Wismajorvik said:


> Off topic, on my first ship the hf tx was only equipped with 6,8,12 and 16Mhz.


I had the same on the Clan Maclennan, can't remember which make of transmitter, it could well have been the same as posted by david.hopcroft above from faint memory it looks familiar.


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## Wismajorvik (Dec 29, 2011)

david.hopcroft said:


> Ref #13
> 
> Wismajorvik..
> 
> ...


That was it. 60 watts if I recollect.


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## david.hopcroft (Jun 29, 2005)

You pulled out a tuning slug - right out for 16mhz - and cracked your head on it each time you got up from the chair to throw the switch to change the G12 from MF to HF !!

It was here - GWWJ - Outside only access to the Radio Room. You may be able to see the door just behind the bridge wing.

David
+


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## gwzm (Nov 7, 2005)

I've just had a quick squint in my very tattered PMG Handbook 1961 edition, page 71, para 82 where it says "All ship stations equipped to work in the authorised bands between 405 and 535 Kc/s must be able to:
(a) send and receive class A2 emissions on 500 Kc/;
(b) send, in addition, class A1 and A2 emissions on at least two working frequencies;
(c) receive, in addition, class A1 and A2 emissions on all the other frequencies necessary for their service.
The provisions of (b) and (c) do not apply to apparatus provided solely for distress, urgency and safety purposes."

From which: (b) means that ships weren't limited to only two of the working frequencies 425, 454, 468 and 480 Kc/s while (c) covers the point if 448 Kc/s is required, although I never heard of it.
That said, as far as I can recall, every ship that I sailed on had all four MF working frequencies.
Happy days,
gwzm


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## Ron Stringer (Mar 15, 2005)

gwzm said:


> (b) send, in addition, class A1 and A2 emissions on at least two working frequencies;
> (c) receive, in addition, class A1 and A2 emissions on all the other frequencies necessary for their service.
> The provisions of (b) and (c) do not apply to apparatus provided solely for distress, urgency and safety purposes."


The ITU Radio Regulations and the UK Radio Rules did not specify the maximum number of frequencies that had to be available for transmission, only the minimum provision. However as standard the UK GPO only licensed two MF working frequencies in the 1950s and 1960s. I assume that additional frequencies were obtainable if the owners applied for them, because I sailed on and encountered vessels that had all 4 of the listed frequencies. One was a Shell tanker and I suspect that, being major company with its own radio superintendent, they had some clout in getting their way. I also sailed with ships of smaller companies that did not have that advantage (or couldn't be bothered to ask).

I sailed with the Oceanspan I, which had variable MF oscillator tuning using a miniature 'starting handle' to wind up the frequency required. That was no problem when working any station - whatever they asked for you could give them.

I also sailed on vessels that had crystals fitted for all 4 working frequencies but only 2 of which appeared on the Ship Radio Licence (one of which instances caused me some hassle with the Aussie radio surveyor in Melbourne).

Para. c) above really has no relevance since it applies to provision on the ship for reception, not transmission.

As I said, as time passed and technology moved on, such small matters faded into the background and the GPO Radio Surveyors found something else with which to torment us shore technicians.(Jester)


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## gwzm (Nov 7, 2005)

Para 730 of the Multilateral Telecommunications Act, October 1947, states "In addition the frequency 512 kc/s may be used in Regions 1 and 3 and 448 Kc/s in region 2."
Later on, The Code of Federal Regulations of the United States of America 1949-1984 states "The frequency 448 kc/s will not be available after July 1, 1970."
So, it looks like 448 Kc/s pre-dated most of us.

Happy days,
gwzm


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## Ron Stringer (Mar 15, 2005)

Varley said:


> I know there were a lot of Irish in Macaroni Ron but I didn't realise Chelmsford had had to impose a potato limit


My smarter-than-me phone substituted 'potato' for 'possible'. Don't ask me why.


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## Varley (Oct 1, 2006)

Apple will tell you that is impotato.


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## cajef (Feb 8, 2012)

gwzm said:


> That said, as far as I can recall, every ship that I sailed on had all four MF working frequencies.


Same here, all the companies ships I was RO on in the sixties had the four working frequencies, they included CP, Ellerman City Line, PSNC, Regent Tankers, Clan Line and Bowaters.


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## R719220 (Oct 5, 2011)

I was at sea (for all too short a time) from 1960 for just over 4 years. Always with IMR. During that time I sailed on 11 ships including short term leave reliefs. Not one of them had the choice of more than two M/F working freqs.

Apart from the IMR51 and IMR81 M/F Tx's, I only ever sailed with one other M/F Tx. It was also IMR but can't remember the designation, possibly the IMR36(??). I did a Xmas relief for the second half of December, 1961, on South American Saint Line's St Essylt/GBSW paying off in Bremen 29 Dec 1961. This also had only two working freqs. Slightly off topic this Tx had (iirc) only two valves, the MO and PA, but also, and what I remember best about it was the Tx had two ccts for 500. One was the normal xtal but the other was an LC cct which was very handy for calling coast stations going down the channel. A bit more bandwith plus sounded better than the normal IMR MF MCW tone which was a bit crappy.


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## Buck Taylor (Apr 19, 2019)

Paul Braxton said:


> Ships were fitted with all the frequencies you quote; all with dedicated crystals, in the case of the Oceanspan transmitter, say, until the later transmitters with synthesised drives came along. That gave you a bit of leeway. If you were working Nitonradio/GNI, for instance, you would probably go for 468, his working frequency being 464, or Landsendradio/GLD, who was on 438 and would often use 425 from the ship. It got a bit congested in European waters (Scheveningen/PCH was on 461, so you would use 468 or maybe 454 with him. Hopefully the relative distances between stations would lessen problems with interference). That's how I used to work, anyway. Somehow it worked out alright.


Nitonradio's working freq of 464khz used to break through the trannie radios in the solent area when most domestic receivers had an I.F of 465khz


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## majoco (Oct 15, 2008)

On most (some?) ships, the antenna feed to the main receiver came from the transmitter in between the antenna tuner and the PA stages. With the transmitter tuned to match the antenna, the receiver was 'tuned' as well, giving maximum signal transfer if you picked a frequency nearest to the coast staion. Of course, the receiver was disconnected by the keying relay in the transmitter and further protected in the receiver itself.

Without this receiver tuning, I doubt it I could have made a great contact with Niton Radio from the Straits of Hormuz. The "Old Man" had left the departure message to send back to London on my desk during the night and I saw it there at 0600 coming on watch. Copied the traffic list and tuned back to 500kHz to hear Niton call CQ to QSY to his traffic list on 464kHz. Tuned down and there he was, quickly turned on the transmitter and tuned up on 468kHz - he was still sending his list and the weather. Nobody called him that I could hear so I gave him a call - to my surprise he came straight back. I sent my MSG - he asked me for a TR and I had to repeat it - perhaps he didn't know where the Straits of Hormuz were! He finished up with "You get today's prize"!


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## searover (Sep 8, 2007)

I thought I remembered lots from my 1950s and 60s afloat but this thread stirred up long forgotten knowledge. Thanks. All the ships I served on had all those freqs (not 448) but I seem to remember we dialled it in on an Oceanspan or Worldspan - not crystals. Any idea what the name was of our Marconi SSB Tx? There we definitely had crystals that were in controlled hot ovens to keep their freq. stable. There were lights on the front that showed the power to the ovens going on and off. Also there was a little round window to keep and eye on the output stage valves. They had to be "cherry red" hot.


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## Wismajorvik (Dec 29, 2011)

majoco said:


> On most (some?) ships, the antenna feed to the main receiver came from the transmitter in between the antenna tuner and the PA stages. With the transmitter tuned to match the antenna, the receiver was 'tuned' as well, giving maximum signal transfer if you picked a frequency nearest to the coast staion. Of course, the receiver was disconnected by the keying relay in the transmitter and further protected in the receiver itself.
> 
> Without this receiver tuning, I doubt it I could have made a great contact with Niton Radio from the Straits of Hormuz. The "Old Man" had left the departure message to send back to London on my desk during the night and I saw it there at 0600 coming on watch. Copied the traffic list and tuned back to 500kHz to hear Niton call CQ to QSY to his traffic list on 464kHz. Tuned down and there he was, quickly turned on the transmitter and tuned up on 468kHz - he was still sending his list and the weather. Nobody called him that I could hear so I gave him a call - to my surprise he came straight back. I sent my MSG - he asked me for a TR and I had to repeat it - perhaps he didn't know where the Straits of Hormuz were! He finished up with "You get today's prize"!


Every ship I was on had a separate receive antenna (two on a couple of ships).


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## majoco (Oct 15, 2008)

I didn't say there wasn't a separate receive antenna - you could switch it to the main receiver via the antenna switch panel but it wasn't as effective as the 'tuned' antenna.


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## Wismajorvik (Dec 29, 2011)

majoco said:


> I didn't say there wasn't a separate receive antenna - you could switch it to the main receiver via the antenna switch panel but it wasn't as effective as the 'tuned' antenna.


Must admit memory not the greatest but I don’t recollect any connection to a receiver from the innards of a transmitter. Maybe that was a MIMCO thing.


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## Ron Stringer (Mar 15, 2005)

SeaRover post #30 

It was probably the NT201 transmitter which was designed for military naval use but purchased and fitted aboard some passenger liners and, of course, the RFA vessels. Less possibly, remotely so, it might have been one of that transmitter's successors (NT202/203/204).

They were produced and marketed by Marconi Wireless Telegraph Company Limited and not by Marconi Marine.


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## Ron Stringer (Mar 15, 2005)

*Routing Of Receiver Antennas Via Transmitters*

I never sailed with, or went aboard to install or repair any Marconi radio station that routed any receiver antennas via the transmitter. I have seen photos of pre-WW2 installations where, at the top of the transmitter antenna unit, there was a lever and knob marked 'Send/Receive' but I never met that arrangement.

I can't imagine trying to work traffic while having to jump up and down changing over the lever position between sending and receiving the reply!


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## gwzm (Nov 7, 2005)

All the ships that I sailed on in the early/mid-1960s had separate aerials for
receive, either whips or wire. The TX keys were Marconi 365s with the additional contacts operated by an insulated bar at the back of the key arm for muting the RX.
Happy days,
gwzm


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## R651400 (Jun 18, 2005)

Ron Stringer said:


> I never sailed with, or went aboard to install or repair any Marconi radio station that routed any receiver antennas via the transmitter....


Neither have I sailed with such an arrangement but interesting on immediate post WW2 Marconi line-up Oceanspan Mk1 tx CR300 rx and Auto Alarm type M the Oceanspan main and emergency aerial were switchable pushing a hefty knob to a slide switch. 
On the same panel a receiver output socket marked "Emergency Aerial" to patch to the CR300 if and when required.
Fading memory Leith Nautical practical instructor Fred Boettcher demonstrating the transmit/receive possibility using the slide swiitch remarking "Really no other choice if your receive aerial has blown away."
Appreciate there must have been some transmit prevention interlock when using this socket patch but memory fails me. 
Desensitising on the CR300 and later Mercury/Electra combo was an additional RF stage cathod bias resistor reducing gain when switched in and out by the back contacts of the Mimco 365 key.


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## djringjr (Feb 11, 2008)

USA Registered ships were required to have 444 kHz for communications with "US Government stations) installed on the main MF transmitter, the Reserve Transmitters only had 410, 425, 468 and 500, while the Main Transmitter added 444, 480 and 512 kHz. USCG Cutters had 466 as a working frequency.

73

David J. Ring, Jr.
N1EA 

Ex WSC and various merchant ships.



Ron Stringer said:


> Tony,
> 
> The 448 experiences were 1960s during which time I sailed on/near the US on 4 ships where US stations (especially USCG stations accepting OBS and AMVER messages) regularly directed me to 448 kHz. Which none of the ships carried.
> 
> ...


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