These transmitters consume insane amounts of power. Per Wikipedia, that's 500 kW of rated transmission power for this one [1], so probably a solid megawatt of grid power input.

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

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yakkers 5 hours ago | parent | next [-]

Doesn't excuse CHU: two 3kW, one 5kW ERP.

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.

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ggm 3 hours ago | parent [-]

Wave skip? (Naieve question)

	▲	yakkers 13 minutes ago \| parent \| next [-]
		HF propagates through skywave (most reliably from 5-30MHz), which is where the signal bounces off the ionosphere. 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.
	▲	intrasight 2 hours ago \| parent \| prev [-]
		https://en.wikipedia.org/wiki/Skywave Bounce off ionosphere

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reaperducer 6 hours ago | parent | prev [-]

Is that emitted power, consumed power, or effective radiated power? Without knowing that, your power calculations have no meaning.

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.

	▲	BuildTheRobots 5 hours ago \| parent \| next [-]
		Also bear in mind that Droitwitch is radiating 3 different services. Talk Sport (1053 kHz), Radio 4 (198 kHz) and Radio Five Live (693 kHz). 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.
	▲	mschuster91 5 hours ago \| parent \| prev [-]
		> Is that emitted power, consumed power, or effective radiated power? Going by [1], emitted power. [1] https://www.bbceng.info/Operations/transmitter_ops/Reminisce...