gareth wrote:
"Scott Dorsey" wrote in message

Perhaps you, as indeed do others seem, are trying to interpret a technique
from
the 1930s and 1940s in terms of the multi-pole Xtal filters that are the
norm today?

Well, yes. That is the point of this thread, isn't it?

No, it isn't.

I have a junk box going back 50 years from which I intend to make the sort
of RX that I dreamed of as a teenager in the 1960s, on the basis that if I
do
not make use of all those museum bits and pieces, the executor of my will
will be likely to bin the lot.

I am inspired by the ham-bands only Eddystone EA12 and am making slow
progress
in a DIY effort to manufacture the gears for the dial drive and am now
considering
the manufacture of a Catacomb along the lines of the National NC100X.

One technique from those pre-mechanical, and multi-pole or monolithic
Xtal, filters was to use a _SINGLE_ crystal early on in the IF chain, and it
is that
single crystal together with its phasing control that interests me at the
moment.

Yes, and you would like to understand how that device works in terms of
modern nyquist filter theory, correct?
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."