Looking back at 1981 and the reception of BBC TV audio on 41.5 MHz in Texas

First of all, let's set the scene for a bit of context.

The original TV system in the UK was known as 405-line and was in use from 1936 to 1985. The lowest TV channel was B1 with the video carrier being on 45.0 MHz.

One unusual feature of this system was that the audio was AM and this was 3.5 MHz lower than the video carrier i.e. 41.5 MHz for Channel B.

Pat Dyer, WA5IYX was a very active TV DXer and logged many TV station over the years. Back in November of 1981 after the peak of solar cycle 21, he managed to hear the TV audio on AM on 41.5 MHz from several transmitters in the UK at his home in San Antonio, Texas.

The distance was about 7500kms and was most likely multi-hop F2 propagation.

Pat is now unfortunately silent key but he did send on the recording to Hugh Cocks, a long time TV DX-er himself and now living in the south of Portugal.

The audio can be heard below. See below the video for a description from Hugh.

Hugh writes... "He sent me the recording many years ago, I can't see it on his own channel so thought it was a good idea to post it on YouTube. There are very few 405 line TVDX recordings in existence.

Mainly BBC 1 from the Divis , Northern Ireland 405 line VHF transmitter on 41.5 MHz.

The Recording starts at 1738 UTC where the regions run separate promos. Divis dominates, around 30 seconds in 'Nationwide' can be heard which is almost certainly from the London area Crystal Palace transmitter on the same frequency.

At least one other signal is there too, maybe from Wales or Scotland or Redruth in Cornwall.

After 90 seconds or so they all combine to transmit the national news from London,

The rumbling/varying tone in the background at times is the beating together of the AM(amplitude modulated) audio carriers which are on fractionally different frequencies.

405 line VHF transmissions finished in early 1985."

BBC to close another batch of Medium Wave radio transmitters in 2021

In a posting on the 14th of April 2021, the BBC announced that they were going to close the medium wave service for ten regional stations in May & June of this year. With fewer and fewer people now listening to medium wave radio, the BBC felt that the transmitter didn't offer value for money.

"As I have written about in previous blog posts, we have been closing some Medium Wave (MW) transmitters across the UK which no longer offer sufficient value for money for licence fee payers."

"A large and increasing share of radio listening in the UK - including to the BBC - is digital, and the BBC is committed to a digital future for radio. In recent years we have made significant investment in local DAB expansion, all of our local radio stations are available on digital terrestrial TV (such as Freeview), and we have transformed our online and mobile offering with BBC Sounds."

A total of 14 medium wave transmitters will be closed down and these are shown below...

Most of them are reasonably low power with powers between 0.5 to 2 kW. The large one is the 160 kW Radio Ulster transmitter near Belfast which would have been heard all over Europe at night. 

They also announced that four regional transmitters will be reducing their output power.

The current power levels are shown above as it's not yet clear what the new power level will be.

"In addition, the following stations will have reduced MW coverage:

Radio Wales
Impacted areas including North of Snowdonia, Anglesey, Bangor, Caernarfon, Conwy, and Betws-y-Coed and Areas around Wrexham and east of Snowdonia. Still available on, FM, DAB, and online and on all TV platforms (Terrestrial, Satellite, and Cable)

Radio Gloucestershire
With areas around Stow-on-the-Wold being impacted DAB will likely be the best option for most listeners. Available on 104.7 FM around Gloucester, 95.0 FM around Stroud and 95.8 FM around Cirencester. Still available on Freeview/Youview and online (through a smart phone, computer, or smart speaker)"

The BBC announced its intention to close MW transmitters back in 2011. It's likely that more will close in the years ahead.

Link...

1) Next phase of changes to some local BBC radio Medium Wave services - Apr 2021

BBC report shows the impact of a sea path on Medium Wave signals

There has been a very interesting discussion on the Medium Wave Circle forum over the last few days about what kind of distances can be achieved over sea paths during daylight hours. Someone posted an interesting link to some tests that were done by the BBC back in 1936.

The BBC engineers used a 1kw transmitter at Start Point on a headland on the south coast of Devon to calculate the limit of acceptable signal strength which is shown above (extrapolated to a 100kw power level). They used a frequency around 1053kHz which has a wavelength of about 284 metres.

You'll notice how the signal struggles to penetrate inland yet can be easily heard along the south coast. As you can see, the signal strength at Hastings which is 307 kms / 191 miles to the east was the same as at Exeter which was over a land path and only 55 kms / 34 miles distant.

It really does show just how well ground wave signals on the Medium Wave band travel over sea water paths.

The BBC report can be seen HERE

Links...
1) Additional information about Start Point on the MB21 website HERE