Hi Jim,
I need a little more info on your setup.
What version DEM transverter do you have? When you checked with your 847,
were you on the same antenna and was/is there a preamp in line?
Its not uncommon for broadcasters to create IMD in the front-ends of
distant equipment. I have an instance of several FM stations putting
about 1mW, 0 dBm, on the coax of a discone antenna. Haven't found a radio
yet that can handle it.
Shawn
N7LQ
On Sun, 8 Jan 2006 13:24:14 EST Jimk8mr@aol.com exclaimed:
>
> 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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