Bob Tellefsen wrote:
Charles
There is another possibility, at least mathematically.
That is A+B=C, in this case 1830 kHz. For example
610 + 1220 = 1830. This is a classic intermod
product. It would require both sources to be near
enough to some kind of junction to create the IM
product, and the whole thing would have to be
near enough to you for you to hear it.
73, Bob N6WG
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Mixing products are not formed in free space. Some type of non linearity
needs to act to create the resulting mixed products. This could be due
to heavy overload at the front end of the rcvr or something in or near
the antenna system that creates the sum/difference products. To rule out
the rcvr try turning off the preamp and inserting attenuation. If the
products are gone it is likely your rcvr's front end and this could be
solved by adding traps to your antenna system to do a more complete job
of AM BC suppression. It could also be a junction of sometype in the
antenna system that is acting as a non linearity (diode effect ?). I
have had this occur where I joined disimilar metals in the antenna
element. In my case I had used a cheap steel crimp lug to join the 2nd
half of my vertical with the bottom copper pipe. When the rains came I
started hearing BC interference on 160. Replacing the lug with a tinned
copper lug solved that issue.
I suppose a nearby steel wire fence or other poor connections could
generate enough energy to create the carrier, however the BC stations
would have to be fairly close, maybe less than 10 miles ?
Regards,
Brian
N6IZ
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