mercoledì 23 ottobre 2019

Radio Caroline mediumwave maintenance report

On Friday 11 October our engineers made a long planned visit to our 648 transmitter site to give the equipment a general tuneup and service.

It was two years ago when we installed the equipment at Orford Ness in October 2017 and we knew that future access for maintenance visits would need careful planning and arrangement. Not just because it is located on a remote site only accessible by boat, but also our engineers all live 100-200 miles away and have their own busy work schedules. It is testament to the quality of the 25 year old Nautel transmitter and the other equipment which was expertly installed by our engineers that it has run for 2 years without requiring a single maintenance visit - something that was unimaginable when we were out at sea and equipment needed almost constant attention. However, our on site telemetry system reported minor problems following late summer thunderstorms, and over the past month or two our own observations plus comments from listeners were that our signal was not as good as it used to be.

The Nautel Transmitter

On site we found that two of the six power amplifier modules within the transmitter had shutdown (presumably as a result of lightning strikes) and would not respond to a remote reset command. These were manually reset and a general overhaul of the equipment was undertaken. The air filters for the cooling fans were found to be caked in dust and dirt and with these cleaned the airflow is now much better and the amplifier temperature much lower. All electrical connections were inspected for tightness and voltage and meter readings noted to make sure everything was within spec. We also took the opportunity to finely adjust our audio processing since this is much easier to do precisely when you have test equipment such as an oscilloscope and modulation monitor connected to the transmitter rather than adjusting remotely and relying on your ears!

Overall we were impressed as to how clean and the stable the installation was, considering it is so close to a saltwater environment. Various comments received from listeners during Friday all reported improved reception so it was definitely a worthwhile visit and gets our signal ready for those dark winter days when interference levels on the AM band generally increase.

Alan Beech – Transmitter engineer