Tom: The better receiver should go first.

It would seem so.

It's best to use radios with non-identical intermediate frequencies so that
the 2nd receiver does not tune to its own IF.

True. I have the service manual for my DX-392. Its IFs on SW a
1st -- 55, 845 kHz
2nd -- 450 kHz

My Grundig eTR7, a basic radio but the best of my four baby radios, has a 10.7
MHz IF for SW (and?), and its tuning skips the area between 10.4 and 11.0.
There is a birdie at 10.26. I don't know yet what its 2nd IF is -- probably in
the 450-460 range, although that birdie should give me a clue. (440?)

Because the eTR7 tunes down to only 530 kHz and nowhere near 55+ MHz on the
high end, I'm thinking of maybe putting it in front of the DX-392 as a tunable
preselector. It does have good sensitivity and selectivity. Without a
schematic, though, physically finding its IF output to its AM detector will be
a challenge.

But that will all have to wait. Other stuff around me is still breaking, which
I have to fix first.

Barry: I did that with a valve shortwave receiver. It had the usual 455 Khz
IF with fairly broad selectivity. I fed the IF to an aircraft receiver that
tunes from 190 to 550 Khz,
and which has an 80 Khz IF.

Neat! That's the elegance of tube/valve receivers. Modifications are relatively
easy.

73 all,
Bill, K5BY