On 01/17/2014 09:51 PM, Tom W8JI wrote:
Intermod is a function of the TOTAL voltage of all the signal sources at the
point where the diodes are. This is why some systems work with diodes, and
some systems completely fall apart. The problem can come from a hundred
small signals, each signal far below threshold, or just one large signal
near threshold. Impedance also matters, both in band and out-of-band.
Indeed. I've had problems with ICE 196 receiver protectors for
several years. I assume the intermod is generated by the diodes in
those devices, though I do not know that for a fact. The problem
occurs on nights when propagation is very good both in the AM BC
band and shortwave in the 5-7 MHz range. I get some extremely strong
SW BC stations on good nights. All are well below the threshold but
the combined affect of many signals is too much. Removing the ICE
196 clears up the intermod, so I am reasonably certain that is where
it is generated. I need to either find another way to protect my
front end or use band pass filters.
73,
Paul N1BUG
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