UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - Radio Caroline on 648kHz

Edward Huggins · 6th Sep 2021, 12:37 pm

Since my last Thread I've been in touch with the Caroline's Chief Engineer and he has updated me on some of the topic raised:

BANDWIDTH
The upper limit is currently 7kHz or 7.5kHz, at the time of writing he could not confirm. I quote him: "Using our DSPx processor with its digital filter, we are 40dB down at 9kHz which is the stipulated EBU/Ofcom requirement. There is no specific EQ curve such as NRSC, but the processor does have multiband limiting which will tend to enhace quieter HF parts".
He laments the fact that many new AM sets only have an upper limit of 3kHz, let alone 4.5kHz. Given they are often software driven, he cannot understand why more Radios do not use signal-strength-driven variable bandwidth filters.

TRANSMITTER
They are currently using an RCA "Ampliphase" 50kW transmitter, the same as used for Big Ls "Tower Of Power" (Radio London) that needs "10kW of power just to get the filaments/heaters and blower motor working - very inefficient". However there is a new Transmitter with increased power being planned for the Winter to give more Natiowide coverage. But they will not be tweaking the audio processor on this because "many contemporary recordings do not take kindly to agressive AM audio processing".

I hope Members will find this "from the Horse's mouth" update of interest.

6th Sep 2021, 12:37 pm	#1
Edward Huggins Dekatron Join Date: Sep 2015 Location: Southwold, Suffolk, UK. Posts: 8,340	Radio Caroline on 648kHz - More. Since my last Thread I've been in touch with the Caroline's Chief Engineer and he has updated me on some of the topic raised: BANDWIDTH The upper limit is currently 7kHz or 7.5kHz, at the time of writing he could not confirm. I quote him: "Using our DSPx processor with its digital filter, we are 40dB down at 9kHz which is the stipulated EBU/Ofcom requirement. There is no specific EQ curve such as NRSC, but the processor does have multiband limiting which will tend to enhace quieter HF parts". He laments the fact that many new AM sets only have an upper limit of 3kHz, let alone 4.5kHz. Given they are often software driven, he cannot understand why more Radios do not use signal-strength-driven variable bandwidth filters. TRANSMITTER They are currently using an RCA "Ampliphase" 50kW transmitter, the same as used for Big Ls "Tower Of Power" (Radio London) that needs "10kW of power just to get the filaments/heaters and blower motor working - very inefficient". However there is a new Transmitter with increased power being planned for the Winter to give more Natiowide coverage. But they will not be tweaking the audio processor on this because "many contemporary recordings do not take kindly to agressive AM audio processing". I hope Members will find this "from the Horse's mouth" update of interest. __________________ Edward.