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.