At least in VK/Australia, there’s the 2200 meter band, but it’s quite limited (1W power limit, CW/digital only, 135.7–137.8 kHz).
At the same time, as much as I don’t want the AM broadcast band to die, I’d love an amateur band in the lower/middle part of MF/MW.
I meant just the broadcast band 148.5-283.5 kHz. (Though I'd love if 2200m and 630m were just a bit wider.)
> and NDB beacons.
Good point[1]. So 148.5-200 kHz in ITU Region 2 (and keep LowFER allowances on 160-190kHz as a consolation prize.)
https://en.wikipedia.org/wiki/Letters_of_last_resort#:~:text...
https://en.wikipedia.org/wiki/List_of_longwave_radio_broadca...
Rather defensive press release thing from the BBC: https://www.bbc.com/mediacentre/articles/2026/radio-4-broadc...
At 30 ct/kWh, that's 300€ per hour, 7200€ per day and about 2.6 million € a year - for a customer base that is only decreasing.
[1] https://en.wikipedia.org/wiki/Droitwich_Transmitting_Station
And by the virtue of shortwave propagation, it could be heard across the world. For the past month and a half (from when the news of its impending shutdown was revealed) I was regularly picking it up in Australia right up until the bitter end.
In the MF (AM broadcast) band, you can observe this at night - in Australia I can pick up the 50kW Melbourne ABC station (public broadcaster) at 774kHz with a good radio, just about across the entire country.
In the LF (longwave) band, the earth’s surface and the ionosphere start to behave more like a waveguide than skywave. This is actually more reliable/consistent than even HF, but you need massive transmitting antennas due to the large wavelengths involved.
HF also generally wins for distance covered per watt - despite the massive power of Radio 4 longwave, I’d have no chance of hearing it reach Australia.
Radio stations are usually measured by the last of those: Effective radiated power.
You can have a radio station with a 50,000 watt ERP, but running only a 2,500 watt transmitter.
For FM radio stations, it's all about the height of the transmitter above average terrain. For AM, it's about the ground conductivity and frequency.
I once worked at a 1,000-watt AM station that had a signal much larger and clearer signal than the 5,000-watt AM station a few miles away.
I'm not a radio engineer, but I'm sure there are plenty on HN who can correct and clarify what I've written.
My suspicion is that this means an exciter and a stack of amps per service, which then go through a two stage combiner and out to the antenna. There might even be a pair of exciters and amps per service depending on redundancy.
The combiners (certainly for FM/DAB/TV services) also cause cumulative attenuation as the signal gets combined each time, so even if all 3 are radiating at the same power, the first in the chain might need twice as much amplification to make up for losses.
edit: MB21 (of course) has some fantastic technical info about Droitwitch: https://tx.mb21.co.uk/gallery/gallerypage.php?txid=1454&page... and there's some great pics here, too: https://www.radiorewind.co.uk/radio1/droitwich.htm
I believe they're still using a pair of Marconi B6042 transmitters (250kW each, in parallel) to provide at least one of the services.
Going by [1], emitted power.
[1] https://www.bbceng.info/Operations/transmitter_ops/Reminisce...
The program was mostly the same as BBC Radio 4 but it used to diverge at certain times of day. I used to be woken up at 5am every day by my parents clock radio with the farming news which was very dull, but easy to sleep through.
In the USA there have never been commercial longwave stations, though various WWV time signals are broadcast in that band.
That, and Atlantic 252 (I believe now long gone) were what he woke up to every morning.
https://en.wikipedia.org/wiki/Atlantic_252
"Although the transmitter was in Ireland, the signal's reach meant that it was often looked upon as a "UK national station". Reception reports were received from such locations as Berlin, Finland, Ibiza and Moscow."
Vacuum tubes also aren't vulnerable to nuclear weapon electro-magnetic pulses.
However, other than ham radio enthusiasts I guess no one listens to analogue radio anymore.
No idea where vacuum tubes were invented but I'm sure the BBC could find someone to make them.