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another radio question. Receiving stations far, far away

Discussion in 'Hobby Electronics' started by Kate Fights, I Cry, May 13, 2005.

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  1. Thanks for all the replies re: valve vs solid state radios
    There was some very interesting reading and I learnt
    quite a lot in that thread.

    I have another question

    I mentioned one of the radios I had was a transistorized
    table radio. Well this also is a portable radio in that
    it can be run via D size batteries.

    Question is how far a signal have you ever received on a
    portable AM band radio. Some nights, especially in the
    colder weather for some reason I can get stations like
    2DU in Dubbo on the radio. Can't explain why it works
    more in the colder weather but it does. And the station
    comes in well enough that you can hear it over all the
    background noise.

    This too considering I am in SA in Adelaide.

    So with that in mind how far has anyone picked up a
    radio station.
     
  2. **You need to do a bit of book learnin'. Go investigate what you SHOULD have
    learned in school, about 'The Ionosphere'.

    For the record, I have picked up the following:

    * Russia. On an ancient Panasonic Short Wave radio.
    * Sydney radio, on a REALLY old HMV (leather covered, steel chassis)
    transistor radio, out near Grenfell, NSW.
    * 2WS-FM down in Queanbeyan (near Canberra).
     
  3. Radio Moscow - Russia
    Radio Austria
    Swiss Radio International
    Vatican Radio
    Radio Canada

    ummm - lots more..

    It's all to do with propagation - radio signals bouncing off the ionosphere
    and back to earth many hundreds or thousands of kilometres away. Different
    seasons and times of day produce different propagation characteristics
    across the radio frequency spectrum. Sun spot activity also affects
    propagation...

    Look up propagation of radio signals and you will soon learn why it all
    happens, how to make the most of it, and even how to predict it to some
    extent!
     


  4. But I'm talking AM receivers here. Aren't the stations you
    mention short wave?
     
  5. Phil Allison

    Phil Allison Guest

    "Kate Fights, I Cry"
    ** Well said KFIC - and absolutely correct.

    The AM band ends at 1700 kHz - just where the short wave band begins.

    As a long time resident of Sydney I can say that it is (or was) very
    possible to hear several AM band transmissions originating in New Zealand
    whenever suitable atmospheric conditions prevailed, late at night on a
    modest radio.

    The suonds sheep bleating was unmistakable.





    ........... Phil
     
  6. Clockmeister

    Clockmeister Guest

    From a place called Mt. Helena about 30km east of Perth I used to pick up
    Sydney, Adelaide, Queensland, numerous asian AM radio and on the odd
    occasion US and European commercial AM stations at night on my Toshiba
    multiband receiver. I also picked up on my old B/W portable TV GWN channel 3
    (as it was then before it went statewide) from Bunbury about 300km away and
    also Channel 11 in Geraldton well over 500km away.

    One particular night I picked up channel 0, QTV from Queensland for a few
    hours and it was quite watchable.

    The TV was a B/W National portable transistorised model with a single VHF
    rotary tuner and using only the indoor antenna that was attached to the back
    of it. I can't really explain why this particular set picked these stations
    up because my parent's set in the lounge with the external antenna received
    nothing.

    Ironically neither set received the local Perth stations very well because
    we were on the wrong side of a slight hill. I still have the portable TV...


    Regards,

    Clockmeister.
     
  7. We had 2XX here in Canberra on 1,008 kHz, same as 2AD in Tasmania,
    and that could be heard in the background sometimes, since 2XX
    was only 300 watts. Now they have moved to FM, and a sport station
    with races is there, with zero fidelity, offering odds on chances of
    losing all yer dough.

    I have often heard Queensland stations here, and it depends on
    ionosphere refelections etc, and I am at a loss to
    explainn further, but should you be able to erect a long enough antenna
    with a length ideal for the broadcast band, preferably with an L plan
    shape,
    then the two antenna signals can be phase adjusted to prefer the station
    you want.

    It won't be hi-fi.

    But the trouble is most stations are same old boring stuff you get from
    the city stations since they
    have networked them all.

    For short wave, a rotating beam antenna like what the ham radio guys use
    is quite good but
    their beams favour 7, 14, 28, 56 MHz.
    So maybe you shouls tudy the old books about radio wave propagation and
    antennas; many books are devoted just to antennas.

    If you have a non resonant long wire antenna just thrown over the roof
    and running in through a window to your set,
    then its wise to make a good earth for the set, since the antenna signal

    needs a *circuit*, so electrons can move from antenna to ground and back

    One can also use an inductor to earth, then a series tuning capacitor to
    the antenna,
    and take the radio signal from the inductor. The capacitor is then tuned
    so the antenna
    and cap and inductor make a resonant circuit and this often boosts the
    signal you want
    with others close by maybe 15 dB. Noise outside this band will be
    rejected.

    MW and SW depends a lot on antennas. Ask any ham.

    I have to help a ham operator lower one antenna and raise another
    tomorrow.

    The beam we are taking down has 4 rods or 9 metres long each, quite a
    beast.

    Radio interest was real big in the 1950s, when
    guys built all their own gear.
    Now they buy at DSE and plug and play,
    or they use a "virtual" receiver that appears on a PC screen
    so the maouse can be used to alter RF gain noise filtering, selectivity,

    band filtering, side band, et all.
    This approach simply digitisers the RF input signal and
    counts what comes in, then a program is applied to decode the data.

    The radio waves are still there but today's latest receivers are very
    different to what they were
    up to the age of the PC.

    Still, I have several old 7 tube communications sets I'd like to restore

    that an old ham left to me when he passed away a few years back..
    They would have gone to the tip otherwise.
    They can still give pretty good performance, and its possible to add
    digital processing to clean up speach signals.

    Nothing here may be of much interest to hi-fi folks but the old ham I
    knew
    was very interested in the lo-fi side of ham and talking to old mates in
    the UK
    as well as what he could get from his sound system.

    To know more about radio, you have to read books and do experiments.

    Patrick Turner
     
  8. Its hard not to drift off topic to SW.

    But there is a lot to learn about MW or the 550kHz to 1650 kHz band.

    Patrick Turner.
     
  9. Some evnins youse can 'ear Helun Clak speakin loud
    acruss the Tasmin, frum NZ Parlimint.

    Evun the shiip are nervus around her.

    Patrick Turner.
     
  10. As I said:

    It's all to do with propagation - radio signals bouncing off the ionosphere
    and back to earth many hundreds or thousands of kilometres away. Different
    seasons and times of day produce different propagation characteristics
    across the radio frequency spectrum. Sun spot activity also affects
    propagation...

    Different frequencies are affected in various ways by the ionosphere,
    sunspot activity, season, etc. AM broadcast band is at the bottom end of
    what many call "shortwave" and the lowest Australian Amateur Radio band is
    at 1800kHz, just above the AM broadcast band.

    The concept of propagation remains true whether we are talking about AM
    broadcast, LW (long wave - below the AM band) or SW (short wave - above the
    AM band). The only difference is how the actual frequencies behave under
    certain conditions....
     
  11. In the very old days I used to regularly listen to JJ in out of Sydney
    on an old AM radio in my shed most nights in Melbourne.
    ...
    Francis Xavier Holden
     

  12. Sorry about that other stuffed up post.

    http://landownunder.blogspot.com/

    ...
    Francis Xavier Holden
     
  13. Bazil

    Bazil Guest

    I used to have a set that would pick up 3/4 of the way around the planet...
     
  14. Phil Allison

    Phil Allison Guest

    "robert casey"

    ** The OP was clear and very specific:

    " Question is how far a signal have you ever received on a
    portable AM band radio. "


    Shame how many folk do not read as carefully.




    .............. Phil
     
  15. Bazil

    Bazil Guest

    To state the bloody obvious. Americans...
     
  16. Don Pearce

    Don Pearce Guest

    Short wave IS AM. I've received Australian radio stations here in
    England quite often. And generally about once a year we suffer
    co-channel interference on TV from South Africa.

    d


    Pearce Consulting
    http://www.pearce.uk.com
     
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