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Radio Caroline goes legal

Discussion in 'Retro Tech' started by Analoguesat, May 20, 2017.

  1. Terryl

    Terryl Specialist Contributor

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    A terminating resistor was used to balance out the load if your transmitting on the long wire, really not needed for reception.

    Coils are used were space is limited, the coils will shorten the length of the long wire, the more winding's the shorter the antenna has to be, however fopr the antenna to work as good as it can the coils need to be setup for different bands to help with proper reception in those bands.

    Coils can be used for 160, 80, 60, 40, 30, 20, 17, 15, 12 and 10 meter HAM bands to load down and shorten up a long wire antenna, also if your looking at VLF frequency's (630 and 2200 meters) it would be best to use a coil to shorten up the antenna, as a single long wire may stretch out of town in those bands.

    For AM radio bands and international short wave bands you can use a simple inverted "V" setup for ham bands and it will work fine.

    Just remember that the "Band" number equals the length of the wire, so one set for the 160 meter band would have two parts set at 160 meter long, this for a full wave length antenna, (that wold work the best) however you can shorten the antenna by one half or one quarter for 160 meters, (1/2 wave, 1/4 wave) this would also make the antenna work for 80 and 40 meters.
     
  2. Terryl

    Terryl Specialist Contributor

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    So for an antenna to be used on 643 KHz (466.5 meters) you can shorten it by three quarters, winding a coil that has 353.25 meters of wire in the winding, and two stubs of 1/8 wave length ( 58.875 each) for one going in the other going out, (mid span coil loading) this would be a 1/4 wave stub, with a 3/4 wave coil, thus shortening the total antenna's required length quite a bit.

    Electrically it is still a full wave length antenna.
     
  3. Channel Hopper

    Channel Hopper Suffering fools just so you don't have to Staff Member

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    You are Count Zeppelin and I claim my 20 Deutschmarks
     
  4. Terryl

    Terryl Specialist Contributor

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    I can give you 54,674,345 Qadlues instead of the 20 Deutschmarks, (sorry I don't have anything of Earth value here ) but there may be an inter Galactic transfer fee of ten one hundredth of a Venusian mud wringer.
     
  5. Terryl

    Terryl Specialist Contributor

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    And you can just order up a G5RV antenna from any ham store, mine works good out to 550 KHz on the AM radio side.(Receiving)
     
  6. s-band

    s-band Specialist Contributor

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    It would take more than the 30 mins I spent to do it properly but here's a guess at the probability of being able to receive Caroline, during the day, in the east of England. The ITU graph used (attached) is based on a 1kW ERP TX, which is convenient. However, the antenna is electrically short. I've assumed medium, dry, ground and noise levels as shown by the horizontal lines on the graph. The noise levels (red lines) are based on approximate data from here Quick Determination of Medium Wave Coverage – Application Note 15|Resources

    The map shows predicted coverage circles for city, rural and quiet rural (summer) noise levels. It sort of ties in with the coverage area given in the application for which the locations mentioned are shown as red spots. The coverage area prediction would change dramatically if I have the soil type wrong.

    Caroline.jpg

    648kHz was used by BBC World Service so is fairly clear if other stations. MWLIST quick and easy: Europe, Africa and Middle East There are a couple of lowish power ones in Europe and a 2MW one in Saudi. I think that there's a good chance of receiving Caroline over a large area at night, providing that you are in a low noise location. @hvdh, I suppose if you take a trip to the coast you might hear it as it would be a sea path;-)

    ITU.jpg
     
    Last edited: Jun 3, 2017
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  7. hvdh

    hvdh Specialist Contributor

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    Yes s-band, 648 kHz is a clear frequency at the WebSDR in Enschede: Wide-band WebSDR in Enschede, the Netherlands
    Here at home with an active antenna stuck out at the balcony, reception proved to be always worse, so my JRC receiver must wait for better times (if ever).

    Yesterday evening the WebSDR had a rather strong carrier on 648 kHz, maybe that was Caroline testing.
     
  8. Terryl

    Terryl Specialist Contributor

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    I'd try for it but I have a local AM station at 650 KHz running at 22 KW during the day, and WSM in Nashville Tennessee takes the band at night with 50 KW on 650 KHz, so this one may be a bit of luck to try for.
     
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  9. Analoguesat

    Analoguesat Administrator Staff Member

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    648khz is the old BBC World Service frequency from Orfordness isnt it?
     
  10. Chris1979

    Chris1979 Ad eundum quo nemo ante iit.

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    Yes they are using the old BBC world service frequency.

    Apparently kicking out 1kw
     
  11. Channel Hopper

    Channel Hopper Suffering fools just so you don't have to Staff Member

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  12. Analoguesat

    Analoguesat Administrator Staff Member

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    I'll have ago for them once the sun sets on the off chance.
     
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  13. Channel Hopper

    Channel Hopper Suffering fools just so you don't have to Staff Member

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  14. s-band

    s-band Specialist Contributor

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    If your RX doesn't overload you might hear the carrier, at least. An SDR with <1Hz bandwidth? The problem will be knowing which TX you are hearing unless you can see several. From observation, most AM/MW stations are at least a few Hz of their stated frequency. Time to get the Beverage strung out (or use a fence);)

    I had a listen on 648 using an active rod antenna and a modified RTL-SDR. In the early evening I could hear one station playing rap and top 40 with Eastern European voice. The modulation was only just intelligible at ~6dB SNR in 6kHz. It peaked to the SE and Caroline will be NE from here.

    I found this in the archive:

    1296_09-15_2-12-05.jpg

    From 2005 when BBCWS were using 1296 for DRM. It was pointed towards the Continent and I was on the back of the beam so it wasn't very strong.
     
  15. Analoguesat

    Analoguesat Administrator Staff Member

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    Caroline have indeed been granted 1kW on 648kHz. The tx has been obtained and they hope to be properly on air very soon
     
  16. PaulR

    PaulR Dazed and Confused Admin Staff Member

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    When I emailed them a couple of weeks ago they had done some tests into a dummy load but no test transmissions. I don't know what power they had the TX cranked up to either,
     
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  17. Analoguesat

    Analoguesat Administrator Staff Member

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    Blimey the MW band is quiet these days. A quick jump up and down it on the car radio - there isnt much to be heard even though its dusk here when the band should be picking up.

    Nothing noted on 648kHz at all even very faintly in the far distance.
     

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