Back in the old days we did it by trial and error and glommed onto what worked
best. When the digital computer came along, we got a full blown printout of the
inter/cross/spuri mod products across a frequency band and picked a
frequency(ies) for the IF that produced minimum spurious products.

Note the word MINIMUM. There has never been a receiver produced by the
superheterodyne process that is totally free of spurious, including the
magnificent Collins S-line or 51J series of receivers.

Jim



"Paul Sengupta"
shared these priceless pearls of wisdom:

-Blimey, thanks. Any idea how they decide to use these figures? Just out of
-curiosity.
-
-Paul
-
-"Jim Weir" wrote in message
.. .
- Nope. They are all over the map. I chose a random book from the
-library...it
- happens to be the King KX-170B. The high COM IF is 9.0M and the low COM
-IF is
- 861.25k. The high NAV IF is 15.1875M and the low NAV IF is 1.1857M. I
-could
- pick half a dozen books from the shelf and no two would be the same.
-

Jim Weir (A&P/IA, CFI, & other good alphabet soup)
VP Eng RST Pres. Cyberchapter EAA Tech. Counselor
http://www.rst-engr.com