For most, if not all, of the many years I've had my DEM 432-28 transverter
I've been bothered by a swath of crud covering much of the useful 432 band.
Being about 2 miles from a tower loaded with pagers, two FM broadcast
stations, and who knows what else, I kind of figured I just had to live with
it.
Recently, however, I've taken another look and determined that the offending
stuff was the mixing product of a TV channel 23 visual carrier (525.26MHz)
and an FM station at 93.1 MHz creating the FM signal at 432.160. The amazing
thing was that the TV station is 30 miles away and the FM station 10 miles
away.
Yesterday I was able to check things with a FT-847, which was clean, and
also to add a DCI 435-10 bandpass filter in front of the DEM transverter, which
also cleaned up things.
This seems like very poor front end performance in the DEM transverter.
Have other people experienced this problem? Any suggestion as to what might
be
going wrong with mine if this is not a normal condition? The transverter
otherwise seems to be working... the several birdies I could hear on both rigs
seemed even stronger on the DEM than on the FT-847 (and went away on both with
the antenna disconnected).
73 - Jim K8MR
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