On Mon, 15 Mar 2010 20:51:52 -0400, wrote:

It's poor filtering that allows an image of the desired signal. That
image is the intermediate frequency away from the ordinal.

Ordinal as in set theory? Huh?
http://en.wikipedia.org/wiki/Ordinal_number
I think you might mean "original".

If the receiver has a 10.7MHz IF and low side LO injection at:
88.5 - 10.7 = 77.8 MHz
the image frequency will be:
77.8MHz - 10.7 = 67.1 MHz

If the receiver uses high side LO injection, the LO will be at:
88.5 + 10.7 = 99.2 MHz
with an image frequency of:
99.2 + 10.7 = 109.9 MHz

Neither 67.1 or 109.9 can be heard on the FM dial.

There are also spurious responses caused by harmonics of the local
oscillator which I can calculate if you want.

I also like the theory that the LO tuning capacitor is at the end of
its range and that dial cord and "slide rule dial" are mis-adjusted.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558