In message , gareth
writes
Whilst a common feature of the communications receiver in the past,
the antenna trim control no longer appears.

Would this be because modern gear expects a 50 ohm pre-matched feed
whilst in former times a long wire might come directly to the antenna
socket?

"Antenna trim" was usually simply a variable shunt capacitor to
chassis/earth, and only served to attempt to tune out any inherent
antenna inductive reactance (or maybe to provide a bit of independent
fine tuning of the input of the RF stage). It was usually associated
with a receiver high(ish) impedance antenna input. When the input
impedance is low, an antenna trim capacitor will have very little
effect.
--
Ian