The BC-453 was much sought after as a tunable and sharp bandpass
(capable) IF strip for addition to a HF receiver. It
tuned the near standard (at that time) IF frequency of around 455kc (OK,
khz).
By pulling up on the doohickey on top of the 85kc IF transformers, the
primary to secondary coupling was reduced and resulted in a fairly high "Q".
"Single Signal"? Those were the days!

The LM-1 ("crystal calibrator") was, (and is) a very well built
heterodyne frequency meter. OH, how the times have changed!

Old Chief Lynn, W7LTQ since 1948