[Dave Wadman]

You can find a pretty good description (with illustrations) of the AI Mk.XV/AN/APS 4 on pp132, 133, 134 in Martin Streetly's 'The Aircraft of 100 Group'. Publ. Robert Hale, London, 1984. ISBN 0 7090 1043 5.
(much of this information was serialised in the UK magazine 'Scale Models'.

Now, AFAIR, it is long out of print but not too difficult to find through on-line resources.

Some of the information given by Streetly on the XV:

Single CRT display for operator
Scanner 14 inch diameter
Two modes of operation; search & intercept
Wavelength 3 cm with a frequency of 10 GHz
Max range 3.75 miles (experienced operator)
Minimum range 600 feet (experienced operator)

IMO 600 feet is pretty close but that is what's given in the book.

HTH

Dave