There’s a quirk of broadcasting in Europe left over from the earliest days of the medium, which our American readers may not have encountered. As well as the familiar AM band, Europeans and Africans also have a so-called long wave band, on which you’ll find AM broadcast stations between about 150 and 280 kHz. Long wave transmissions were an ideal solution in the 1920s and 1930s to the problem of achieving national coverage from a single transmitter, and were widely used by state broadcasters. In an age of digital streaming they are increasingly irrelevant, and [Ringway Manchester] takes a look at one of Britain’s last long wave transmitter sites at Droitwich not too far from Birmingham.
The site covers around 50 acres, and is home to a variety of both medium wave (AM, for Americans), and a single long wave transmitter carrying BBC Radio 4 on 198 kHz. As he takes us through its history in the video below the break we hear a rundown of most of the major events in British broadcasting, while few Brits will have visited this unassuming field it’s likely most of us will have listened to something sent from here.
The long wave antenna is a T-shaped affair strung between two masts. We’re guessing that the radiator is the vertical portion, with the bar of the T forming a capacitance with the ground to make up for the radiator being a fraction of the 1515 meter wavelength. The video is something of a tribute to this once-vital station, as the Radio 4 transmissions are likely to stop in 2024 and the medium wave ones over the following years. We have to admit to catching our BBC transmissions online these days, but we still have to admit a pang of sadness at its impending end.
This reminds us, we’ve taken a fond look at AM radio in the past.
The 198kHz transmission is also maintained as a frequency reference. There have been disciplined oscillators which lock to it and provide a 10MHz reference for calibration. These also exist for the MSF transmitter on 60kHz (similar to WWV and DCF77) but have mostly been superseded by GPS-locked oscillators.
The 198 kHz sugnal also carries the Radio Teleswitch Service still used for remote switching on some dual-metered electricity supplies. The energy suppliers’ “deadline” for replacing RTS meters with modern smart ones has already been pushed back several times. However. there is an overriding deadline not subject to political whims: when one of the last pair of transmitting valves dies, the service will end.
is there any way to acquire new old stock valves from other decommissioned LW transmitters or other countries? I think when droitwich goes it will be the ultimate tragedy. it can be recieved anywhere in uk from one transmitter – including boats, and I even picked it up in France when I was there.
Jenny,
As a newly recruited BBC Graduate Trainee Engineer, I visited the Droitwich Transmitting Station in the Autumn of 1986.
As we drove up the drive to the Transmitter Hall, I was shocked at the brutalist architecture and the bold frontage of the building. This was truly something from the early 1930s, Imperialist in style, like a lot of architecture from that time. The motto “Nation shall speak peace unto Nation” is clearly visible over the massive front entrance.
Although the pinnacle of 1930’s broadcast technology, my visit was close to it’s 50th Anniversary.
We were still very much in the Cold War years at that time, and it was clear that Droitwich had an important role in maintaining national communications, in the event of hostilities. The staff had secondary roles, to keep the station running 24/7 regardless of what was happening geopolitically around them.
As such the station was built like a bunker, with local staff accommodation, onsite catering and other secure systems, including diesel power generation, separate from the grid, and sufficient diesel fuel in the cylindrical storage tanks to keep the station running autonomously for a period of 3 months.
The transmitter hall had had an upgrade in the 1960s, and again in the 1980s, when high-power RF systems were very much reduced in size to their massive forebears. This meant that wnen I visited, most of the transmitter hall was redundant space.
Those of you who have worked on communications transceivers, will know the requirement to keep each stage of the system screened from each other. This was thee same approach in the transmitter hall, but on a massive scale. It consisted of a row of screened rooms, each about 4m square, visible in the video. By the time of my visit, these screened rooms had been converted into lab space and offices! I remember one of the former screened rooms being fitted out with benches with oscilloscopes, spectrum analysers and other RF test gear.
There was so much 198KHz RF energy floating around, after all Droitwich had a 500kW output to the antennas, that the former screened rooms made excellent Faraday cages! I remember one demonstration, where two metal plates were attached to the wall of the transmitter hall, one of them earthed, with a 100W incandescent light bulb connected between them. The bulb glowed brightly, modulated to the sounds of Radio 4!
We were shown the engine rooms, which at that time had two massive “marine” diesels. These had to be frequently tested, including on the day of our visit, and upon startup the noise was deafening.
All in all a fascinating and most memorable visit to a wonderful historical exhibition of 1930s Broadcast Engineering.
Tech evolves and times change, but there’s still something magical about stringing up a long wire and harvesting your entertainment directly from the aether, the way the good gods Marconi and Tesla intended.
Sadly they never accepted me when i applied tot he same programme :)
there is a long wave antena farm close(10 km) to where
I live,which I use as a reference when giving directions
telling people to turn left at area 52
Here in The Netherlands we have a very beautiful transmitter building called Radio Kootwijk. It’s in the middle of nowhere but certainly worth a visit. Its build like a cathedral and sat in the center of the now gone transmitter masts. Although there is no machinery left. the hall in itself is quite interesting. It was designed in the years of the mechanical transmitters, but soon after finishing building it, tube transmitters were a thing so there was way too much space now. the main hall is now a venue for theater and music perfomances and has a very nice acoustic.
google it to get an idea
Indeed, one of my friends from the Dutch hackerspace scene showed it to me a while back. A cathedral of radio.
Also used as the set for a couple of films:
https://www.imdb.com/search/title/?locations=Radio%20Kootwijk%2C%20Netherlands&ref_=ttloc_loc_2
Thank you for the tip! The building was apparently well built, it has been proven by time. This one surely is on par with some monumental German buildings of the day, if not better. Judging by the photos of back then vs now, it had barely aged. If it was being cleaned, it might look like new, even. Very impressive. 😎
More exterior shots here:
http://tx.mb21.co.uk/gallery/gallerypage.php?txid=1454&pageid=2075
A good view of the 1961 upgrade to the transmitter gallery at timecode 2m:46 on the video.
https://youtu.be/RYjmuwR1cPc?t=166
How on earth did/do they adjust the turnbuckles on the supporting ropes?!
I was bummed out that when I was stationed in Germany my old DX-150A, which unlike the DX-160, did not include longwave.
On the plus side, for FM I just listened to a station in Luxembourg, as it was both in english and played decent rock (at least it did in the late 80’s).
Most likely that was the legendary Radio Luxembourg. It was also very popular in the UK & Ireland and forced the more standard format stations to develop competing services.
> Oh cool, hopefully the video will demonstrate what broadcast over longwave sounds like. Lower bandwidth than medium wave AM would make a difference I would guess.
> Watches video, there is no audio sample anywhere in it.
> Annoyed
> Well.. what would they include? YouTube bots would probably flag it as a copyright violation and mute or remove the video.
> Surely at some point they have been recorded broadcasting something that is in the public domain…
> Yah but would the bot or employee at YouTube recognize or care?
Conclusion: People have collectively made this world suck.
Ok, I searched YouTube and found a few videos. I won’t link any because all I found were mostly just the YouTuber talking with somewhere around 10 seconds of recorded audio several minutes in. But so far as I can tell it sounds just like shortwave.
LW and MW broadcasts sound the same. Same channel spacing, same bandwith.
“As well as the familiar AM band”
I think I’ll never understand why the US had to name a band after a modulation instead of a wavelength, especially considering that the modulation in question wasn’t exclusive to said band at all…
…Because we never had long wave. With the one band we had we made radios simple. Wavelength made for messy math, imagine a digital display dealing in wavelength and clicking to the next slot-channel. Because frequency is non metric or imperial there is no confusion. Something we all agreed on.
I understand. Though on 27 MHz CB radio and AIR band (VHF), there also was “AM” used, technically, so AM wasn’t unique to just medium wave. Those cheap ’80s era multi band receivers (say, Yoko 684) capable of receiving these extra bands still continued to use the “FM” term for the VHF broadcast band (88-108MHz in FM), so I assume the AM/FM naming mistake was apparently never fixed. 🤷♂️
Yup. It somewhat irritated me as a child, too.
The pocket radios I had owned often used the English terms “AM” for medium wave and “FM” for ultra-short wave (aka super-short wave or simply VHF?).
I knew these were modulation names, sure, but I found it misleading/unlogical to name a band selection after them.
If the manufacturers did at least bother to clearly say “AM band” or “FM band”.. *sigh*
Anyway, to be fair, it’s perhaps not only an American ‘problem’.
Cheap transistor radios produced in far east (Hong-Kong, Taiwan, Japan etc) had used same sort of labeling as the American models.
I think it is largely an artifact of cultural perception in the US — as echodelta noted, there was never really commercial use of any AM band other than medium wave, and most radios sold prior to the 1960s had one entirely unlabeled frequency range. A second band only became available on US consumer radios to accommodate FM, so identifying that band with the new capability made sense. The multi-band receivers you referenced above never had much market share here.
FM was also perceived very differently from AM in the US for several decades following its introduction. There was fairly limited simulcasting between FM and AM — and FM stations tended to be used specifically for formats that benefitted from the sound quality (mainly classical, AOR, and public broadcasting, at first). AM was the home of news, talk radio, and more mainstream music. In that sense, the FM “brand” was very distinct from that of AM.
TVs, by contrast, were typically labeled as UHF and VHF. I don’t think most people had any idea that FM radio sat in the middle of the VHF TV channels, except maybe as a party trick in cities with broadcasts on channel 6.
I too toured this as part of my BBC engineer training, and if I remeber rightly the aerial was described as a ‘Craelius T’, all of it radiates but the top of the T is also a massive top-loading capacitor. The sheer power – and utility – of Droitwich came home to me years later while driving through Norway where I could still listen to Radio 4 on Long Wave day after day no matter where I went. Apart from internet streaming there’s no other tech that can do that.