Hi Dick the site of GBR is bounded on the east by Watling Street (A5) and
old Roman road, and to the west by the Oxford canal. It is at Hillmorton
about 4 miles South-East of Rugby (I would say its more 'east' ). There is
an aerial icon on most of our OS maps and roadmaps.

From the 1926 paper (thanks Jim) the masts (hence the capacity hat) are

given as 820 feet high, and the capacity as 33nF. The resistance of the
aerial is quoted as 0.7ohms or with the loading coil used at that time about
0.85ohms (The coil was changed when the TX was phase stabilised in the late
1960s). The coil is quoted at 2500uH at 16kHz and a resistance of 0.11ohms.
The power is usually a nominal 500kW. In the old valve days this was
probably about 200kW to 250kW to the aerial, with an aerial current of about
500amps. The figures indicate about 50% efficiency in the PA. There is no
aerial efficiency given but there may be enough data there for you to
simulate it. I suspect the PA efficiency is higher now (I am certain it is
solid state now) but I suspect the power to the aerial is the same. The
aerial feed-though is a bit suspect above about 750amps (!!)  I was told.

I hope that is helpful
Cheers de Alan G3NYK
[email protected]