Ships' working frequencies - Page 2 - Ships Nostalgia
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Ships' working frequencies

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  #26  
Old 14th August 2019, 12:56
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Quote:
Originally Posted by gwzm View Post
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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  #27  
Old 14th August 2019, 15:29
R719220 R719220 is offline  
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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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  #28  
Old 15th August 2019, 23:25
Buck Taylor Buck Taylor is offline
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Quote:
Originally Posted by Paul Braxton View Post
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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  #29  
Old 16th August 2019, 02:37
majoco majoco is offline  
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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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  #30  
Old 16th August 2019, 06:59
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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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  #31  
Old 16th August 2019, 08:47
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Quote:
Originally Posted by majoco View Post
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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  #32  
Old 16th August 2019, 08:52
majoco majoco is offline  
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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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  #33  
Old 16th August 2019, 09:08
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Quote:
Originally Posted by majoco View Post
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 donít recollect any connection to a receiver from the innards of a transmitter. Maybe that was a MIMCO thing.
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  #34  
Old 16th August 2019, 10:36
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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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  #35  
Old 16th August 2019, 10:42
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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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  #36  
Old 16th August 2019, 23:52
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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,
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  #37  
Old 17th August 2019, 15:46
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Quote:
Originally Posted by Ron Stringer View Post
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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  #38  
Old 22nd August 2019, 23:56
djringjr djringjr is offline  
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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.

Quote:
Originally Posted by Ron Stringer View Post
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.

Last edited by djringjr; 23rd August 2019 at 00:00..
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