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Old 19th Oct 2020, 10:05 am   #1
Edward Huggins
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Default Great Sound on MW!

Last night I was listening to Radio Caroline (648 AM) on our large SONY FM IC Pre-Set Portable. It sounded unexpectedly clear given the standard AM range on this set, albeit a high-end model.

It made me think of those Pirate Ship Transmitters that used the RCA "Paraphase" (?) transmitters, that deliberately provided an extended HF i.e. no "clipping".

Although all those 1960s Trannys had standard IF Bandwith limiting to 4,500 cps, they did sound bright and clear at the time. Of course, that's maybe perception rather than reality.

Can other Members speak more as to just how these Transmitters were configured and if Broadcasters still use this process today, indeed today's Radio Caroline perhaps?
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Old 19th Oct 2020, 10:59 am   #2
Andrew2
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Default Re: Great Sound on MW!

RCA Ampliphase. Apparently they were bu&&ers to set up and keep in line, but very efficient as they used two class-C PA stages rather than a linear amp. Sadly, Caroline as received up here isn't really of sufficient quality to judge the b/w by ear, but a look on my SDR might help.
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Old 19th Oct 2020, 11:03 am   #3
boxdoctor
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Default Re: Great Sound on MW!

Hi Edward.
The system of modulation you refer to is "Ampliphase"
You will find some info on it on Wikipedia, and yes, it did seem to give tHe impression of the transmitter having more output than it actually had.
Obsolete now, according to Wiki, but good in its day!
Of course, we all heard better in our younger days, so that, perhaps, adds to the impression of it being a "better" system. Tony.

# Post crossed with Andrew2
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Old 19th Oct 2020, 12:06 pm   #4
MurphyNut
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Default Re: Great Sound on MW!

I'm amazed at how good MW can still sound on a 1930's radio, particularly BBC Radio 5 Live, extremely strong and clear station......unfortunately it's mostly people talking about sport which I have absolutely no interest in whatsoever!
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Old 19th Oct 2020, 7:40 pm   #5
Edward Huggins
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Default Re: Great Sound on MW!

Thanks for informing me. I now realise that it's not just about the nature of the Transmitter per se, it was also the audio processing and pre-emphasis that preceeded it.
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Old 20th Oct 2020, 12:03 pm   #6
Junk Box Nick
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Default Re: Great Sound on MW!

When finally the BBC close down Radio Wales on 657 Radio Caroline on 648 will sound great on my Hacker Sovereign II.
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Old 20th Oct 2020, 6:55 pm   #7
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Default Re: Great Sound on MW!

Always remember that by their nature the 1960s MW Pirate-stations didn't worry too much about the 'accepted' fit-into-a-10KHz-channel broadcast-standards-of-the-day. Winding-up the treble so your station sounded 'brighter' aqnd 'fresher' - yeah, if your transmitter could handle it - go for it!

They did - and we loved them for it. So much better than the Churchillian 'mellow bellow' of the Beeb.
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