Honus wrote:
And now I'm hearing a memorial to Gene Scott on 1615 (MW, of course) at 0555
UTC. It's identical to the broadcast that I'm receiving clearly on 5755
(KAIJ, TX)

You're receiving the 5755 transmission on 1615 because of the third
harmonic of the radio's local oscillator. (i.e. they are NOT actually
transmitting on 1615)

When you tune to 1615, the radio tunes an internal oscillator to
2070KHz. This 2070KHz signal is mixed with the 1615KHz signal (if there
was one). You get four outputs: 1615, 2070, 2070+1615=3685KHz, and
2070-1615=455KHz. The selective circuits in the intermediate frequency
amplifier only pass the last signal at 455KHz, and that's what you hear.

But the internal oscillator is not perfect. It generates "harmonics" on
multiples of the frequency to which it's tuned. 2070KHz,
2070x2=4140KHz, 2070x3=6210KHz, 2070x4=8280KHz, etc... (they get weaker
as the multiplier increases)

If any of these multiples can mix with a signal to generate 455, then
that signal will be heard as well.

And in this case, it can. 6210-5755=455. The KAIJ signal will mix with
the 3rd harmonic and will be heard.

Your reception of Cuba on 1697 is probably from the same phenomonon. I
note that when tuned to 1697KHz, the local oscillator is on 2152KHz.
2152x3=6456, and 6456-6001=455. So if Radio Havana was broadcasting on
6001KHz, you'd hear it on 1697. Monitoring Times does list Radio Havana
as being on 6000KHz at 0530z.
--
Doug Smith W9WI
Pleasant View (Nashville), TN EM66
http://www.w9wi.com