Friday, 17 September 2010

History of ships' radio room clocks


Remember when all ships had real radio operators? If you do you'll know that the ops had to maintain "silent periods" when they wouldn't transmit, instead listening for distress calls on 500kHz and 2182kHz. For this they had a special radio room clock with sectors marked on it.

After the loss of the Titanic, the radio frequency of 500 kHz became an international calling and distress frequency for Morse code maritime communication. For most of its history, the international distress frequency was referred to by its equivalent wavelength, 600 meters, or, using the earlier frequency unit name, 500 kilocycles [per second] or 500 kc.

2182kHz was added later and transmissions on 2182 kHz commonly use single-sideband modulation (SSB) (upper sideband only). However, amplitude modulation (AM) was often used in some parts of the world.

Maritime coastal stations used to maintain 24 hour watches on these frequencies, staffed by highly-skilled radio operators.

As a reminder, a ship's radio room clock would have the 500kHz silence periods marked by shading the sectors between h+15 to h+18 and h+45 to h+48 in RED. Similar sectors between h+00 to H+03 and h+30 to h+33 were marked in GREEN, which is the corresponding silence period for 2182 kHz.

Anyone breaking the rules would soon hear "QRT SP" in Morse Code, meaning "STOP SENDING - SILENT PERIOD!"

I've always wanted to have one of these clocks for my own shack, but couldn't find one. So … I decided to make one. I spent two days with a graphics program recreating a radio room clock from the Winthrop Clock Company of Boston, Ma., USA. It wasn't easy, but I then took the finished result, printed it and pulled apart a quartz clock that I bought for the job and installed it - what a lot of work!

The end result is shown in the photograph above and creates quite a lot of attention in my shack. It also keeps time really well too!

There is even The Radio Maritime Day each April where you have to obey the silent periods, so it comes in useful

Anyway, after all that work it seemed a shame to waste the artwork. I then found that I could upload it to a company called CafePress, letting people buy their own clock. While I was there I also designed some T-shirts, mugs, mouse mats and other goodies.

These products, including a reproduction radio room clock, let you relive those bygone, halcyon days when "sparks" ruled the maritime airwaves. So your shack can now look like a ship's radio room!

If you are in the UK go to http://www.cafepress.co.uk/theradioroom or if elsewhere http://www.cafepress.com/theradioroom – you can select the currency you wish to pay with.

I have one of the new Cafe Press clocks - it is about 10 inches in diameter and very striking. It is quartz powered so keeps good time and the tick isn't too loud either. Looks very nice on the wall and not too expensive either.

But remember QRT SP!

12 comments:

  1. I have one of those clock reproductions. Works fine. The real thing, now an antique, can go for $1000 and higher. 73 Dick

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  2. Thanks Dick - probably keeps better time than the old clockwork ones too! 73 Steve G0KYA

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  3. On a related topic you should take a look at a book describing the English government's search for a way to determine longitude at sea, which required a chronometer that would remain accurate under those conditions:
    http://www.amazon.com/Longitude-Genius-Greatest-Scientific-Problem/dp/0140258795

    A fascinating read.

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  4. Yes, the great John Harrison - there was a brilliant TV adaptation on the BBC some time ago called "Longitude".

    You can still get it on DVD - see:
    http://www.amazon.co.uk/gp/product/B000L42N96?ie=UTF8&tag=cringlefordsc-21&linkCode=as2&camp=1634&creative=6738&creativeASIN=B000L42N96

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  5. Aha one of my favourite books of the last 10 years - "Longitude". In Oz I was a CB guy on SSB for 3 glorious years and an SWL for the same time 1997 to 2000. It was a sad day when my 5/8 vertical was taken down and the wire rolled up, the radios put "in storage" with a friend (I expect to never see them again BTW). But how your story got to me, was it reminded me how habitually in the Central West of NSW I used to tune my FRG7700 to 2.182 USB whnever I was reading a book or not particularly searching for anying, just in case I heard something that was important and maybe even I could use the phone to alert the right people. In those three years I can remember earing a thing, but it didn't stop me listening! all the best, Scotty

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  6. I hope you take part in the annual MRD events :-)

    73 de OH8XAT (ex DRKF)

    and remember! QRX3 SP AS

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  7. Bit disappointing that it wasn't modeled after a good old British Smiths Astral radio room clock! :-)

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    Replies
    1. If you can get me the face off one I'll do it! Or at least a good scan of one.

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  8. Best I can suggest is you pinch one off the 'net :-)

    http://www.sellingantiques.co.uk/261219/smiths-red-green-segment-radio-room-clock/

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  9. Hi Steve , fascinating blog , I am in a similar position regarding clock face design , but with a bit of a twist .. i am constructing this car ,

    http://www.rodsnsods.co.uk/forum/garage/medusa-206057


    and for the dash vintage rev counter i am using this old radio room clock ...

    http://i32.photobucket.com/albums/d44/ivanhoew/medusa/IMG_3165_zpsmklngfwj.jpg

    http://i32.photobucket.com/albums/d44/ivanhoew/medusa/IMG_3164_zpsyh1id3nn.jpg


    I want to make get a dial printed with rpm on it , basically 0to 6k going from 8pm to 4 pm. can you point me in the right direction as to how you did yours ?


    regards
    robert.

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    1. Hi Robert,

      Just did a double take there - I thought I had seen TWO Jaguar straight six engines, then I realised I had! I started by scanning a clock face and then went to work with Photoshop. It took me two days, but I got the result I wanted. The Photoshop file had nearly 40 layers with everything separate so that everything was independent. Best bet is to find a tame graphic designer unless you are familiar with Photoshop.

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  10. wow 2 days !! , i will cast about for a friend with ps experience , hopefully mine will be a bit simpler with just a white background and black numbers . Thank you for the pointers .:)
    regards
    robert.

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