Radio Caroline 648kHz

[Crackle]

I am certainly no expert on radio propagation, but I suspect the reason for the exceptionally good signal that many are getting up and down the country is because of the location of the transmitter, which is alleged to be at Orford Ness, I believe the site of the old BBC World Service and the experimental radar early warning systems.
The land all around is very flat and it has very close proximity to the sea, which makes the best ground plane possible, infact it has water on both sides as the site is on a long peninsular.

Mike

[Murphyv310]

Hi Mike.
Its certainly not alleged that its Orfordness its fact. The site was well known for the strength of signal and ideal location. In the Caroline blurb I linked to they explain the site already had an antenna tuned to 648kHz, so again confirming the location.

[ppppenguin]

This was the old MW World service trasnmission site. Hence the availability of a 648kHz antenna.

[Terry]

Unless there is some ant-farm magic going on I'm  beginning to get a little bit suspicious of the 1Kw claim ...

Who would not like to see how they're managing the performance on so little grunt.

I am certainly no expert on radio propagation, but I suspect the reason for the exceptionally good signal that many are getting up and down the country is because of the location of the transmitter, which is ... at Orford Ness, ...
The land all around is very flat and it has very close proximity to the sea, which makes the best ground plane possible ...

Here's an interesting comparison: I don't know how high the 648kHz antenna at Orford Ness is but the mv Caroline's mast rose 168ft - ~51m - above the deck. Caroline's transmitter power was 10kW (there were, in fact, two 10kW transmitters on board but they could only be operated one at a time).

The current Caroline power of 1kW is ERP. For comparison purposes, anybody got any idea what the mv Caroline's ERP was? I assume that the mv Mi Amigo, also 10kW from a 165ft  (~50m) mast would have performed similarly. Also, I was once told by the chief radio engineer, Carl Thompson, on the Mi Amigo that the tide affected the signal level into London by three S points, depending on the ship's alignment. What this means in dB I haven't a clue, but it sounds rather a lot to me!

Nevertheless, both ships covered a lot of their respective ends of the country with 10kW after the Caroline/Atlanta merger so is it so surprising that 1kW over a relatively flat landscape can cover so well? No ant-farm magic required!

[Geordie McBoyne]

Make that one of my first radio jobs to do when I return home. Tune my Pilot X65B to 648Khz. The set is connected to the tunable frame aerial.

Geordie McBoyne.

[Synchrodyne]

I was of the impression that the former BBC 648 kHz WS transmitter at Orfordness used a multi-mast directional array primarily intended to project a skywave beam towards Europe, pointing more-or-less towards Ghent.  For UK domestic reception, an omnidirectional or mildly directional aerial (squashed circle, with the squash around ESE side) would, I think, be more appropriate, perhaps with antifading characteristics to maximize the ground wave and minimize the skywave, although as far as I know, antifading radiators were not much used with input powers of less than 10 kW.

Cheers,

Steve

[Raditechman]

Reading about the Orfordness transmitter site, it seems that there is also an omni-directional 648KHz back up aerial there for use if the main aerial was out of service. Possibly that is the one Radio Caroline is using.

John

[Crackle]

Wikipedia has a lot of information on the Orfordness station.
https://en.wikipedia.org/wiki/Orfordness...ng_station

Mike

[colly0410]

Had a tune in on the car radio on Mapperley Top (about highest point around) on Nottingham outskirts earlier on tonight & there was a pulsating chuffing sound, from some CCI I presume. It was fading in & out & every now & then the station would come in clear-ish then go back to the chuffing sound...

[Crackle]

I have noticed the term CCI used frequently in this thread, I couldnt work it out and had to look it up. (sad eh)
It has hundreds of meanings but I assume you people are referring to it in this case as co-channel interference.
All I can say about using a term like this with no explanation is, IHTUOAWTBE.
Oh no now I have done it, I bet you wont find that answer, or for ICE, in Wikipedia.
Mike