"Scott Dorsey" wrote in message

Arny Krueger wrote:

Perhaps the most impressive item in teh system was the
spectrum analyzer. Balanced mixers converted three
adjoining
frequency ranges of the inbound signal to the same range
of
intermediate frequencies which passed through three
identical sets of additional tuned circuits and
rectifiers
to provide a fast-response spectrum analysis of the
inbound
signal as the antenna rotated.

AN/APR-6?


The AN/MPQ-34 had the spectrum analyzer, the AN/MPQ-39 had
over 400 subminiature tubes.