On 7/4/2020 4:35 PM, Rob Atkinson wrote:
I'm not following the reasoning here. How are listeners never fighting noise below 1710 kc? In some cases noise (or by noise are we thinking of QRM?) is worse on medium wave broadcast channels because noise is usually AM and so are the desired signals. Also the receiver passband is wide. Those TIS stations usually run only 30 to 50 watts and use physically small antennas. 73 Rob K5UJ
If I listen on my 90 foot vertical, and get a noise level check at, say, 1750 kHz and then start tuning from 1710 kHz down, there will be no channel where the S-meter gets down to the reference noise level at 1750 kHz. This isn't because there is more noise below 1710 kHz; rather every channel has one or more stations that are well out of the noise. This will be true no matter what receiver bandwidth is used. Especially at night. There may be signals buried in the noise, but they will always be covered up by stronger signals. When I had my beverages up, I remember hearing TIS stations up to 100 miles away, FWIW. I don't know what "noise is usually AM" means. 73 Rick N6RK _________________ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector