Even the DNO get it wrong sometimes.

Yes I used to hear the N Ireland transmissions regularly at nite sometimes with almost armchair quality reception. I think the masts are called Blaw Knox masts and as ýou say an unusual design popular with US commercial stations. The station on 1296khz is an Asian station transmitting from Ashton moss transmitter near Birmingham I think if memory serves it runs about 5.5 Kilowatts I remember it was usually stronger than the BBC world service which proves just how efficient the BBC areals at Orford nesss were. My daytime reception here is Radio Caroline but only just on 648khzBBC 5 from start point on 693 radio Wales  on 881khz radio5 from Bournemouth on 909khz Jersey on 1026 talksport weakly on 1053 and much stronger on 1089 Guernsey on 1116 some Indian  program from brookmans Park on 1458 and finally BBC Somerset on 1566. At nite of course things get much more interesting!

BBC Radio Ulster from Lisnagarvey had a radiated power of 100 kW and in the past I was often able to listen as far south as Dublin.

Did you ever receive Downtown Radio on 1026 kHz? It was broadcast from a small transmitter site at Knockbracken, just to the south-east of Belfast, with a radiated power of only 1 kW.

As for Orford Ness, I believe the BBC MW antennas there were directional towards the North Sea and the continent and as a result reception in the UK would have generally been poor, relying on whatever back-beam existed.

Interestingly, BS 6656 used to have a note that certain tables contained therin relating to the ignition of flammable atmospheres by radiofrequency radiation did not apply to '. . . locations on the seaward side of Orford Ness, Suffolk' but I think this may have been more to do with the exteremely powerful over-the-horizon radar station that was once there, rather than the MW transmitters!

- Ross

BBC Radio Ulster from Lisnagarvey had a radiated power of 100 kW and in the past I was often able to listen as far south as Dublin.

Did you ever receive Downtown Radio on 1026 kHz? It was broadcast from a small transmitter site at Knockbracken, just to the south-east of Belfast, with a radiated power of only 1 kW.

As for Orford Ness, I believe the BBC MW antennas there were directional towards the North Sea and the continent and as a result reception in the UK would have generally been poor, relying on whatever back-beam existed.

Interestingly, BS 6656 used to have a note that certain tables contained therin relating to the ignition of flammable atmospheres by radiofrequency radiation did not apply to '. . . locations on the seaward side of Orford Ness, Suffolk' but I think this may have been more to do with the exteremely powerful over-the-horizon radar station that was once there, rather than the MW transmitters!

- Ross

That " extremely powerful over-the-horizon radar station" would be the Cobra Mist project. A truly misguided attempt to co-locate transmitter and receiver for an OTHR that was very expensive and was eventually scrapped without ever having really worked, An array of log periodic antennas pointing at incremental angles and many megawatts of towards the iron curtain.

The now declassified official report makes an interesting read for those who like details.

"To achieve sufficient signal-to-noise ratios  against the predicted noise background, the radar
was capable of very high transmitted power output. A peak power of 10 MW and an average power
of 600 kw were originally specified, although these figures were not achieved in practice. Such high
powers were incorporated in the design to compensate for the relatively low antenna gain of
approximately 25 dBs."

Mike

PS good OTHRs are like the Australian one Jindalee Operational Radar Network (JORN)