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unknow radio stations on 27 mc

Posted: Mon Jan 29, 2018 2:01 am
by radiowaz
using HDSDR and a 20 dollar sdr and 40 meter fullwave dipole...see attacted radio spectrum picture,, I still haven't found out where or why I am hearing these am radio stations on 27mc.. any ideas,, very loud and clear. and I live in the middle of the sticks,, nearest big town is Nashville, over 100 miles away.. but these am stations seem to be from all over the country (east of the Rockies ) and Cuba, S. America , French and Norwegian? Question WHY???!! freq 27.090 to 28.185

Re: unknow radio stations on 27 mc

Posted: Mon Jan 29, 2018 2:56 am
by Aussie Susan
Isn't that Citizen Band?
Would not explain the long distance though...
Susan

Re: unknow radio stations on 27 mc

Posted: Mon Jan 29, 2018 3:31 am
by rtlsdrblog
Are you in direct sampling mode? DSM mirrors all signals around the center point of 14.4 MHz, so this is something you need to be aware of.

Re: unknow radio stations on 27 mc

Posted: Mon Jan 29, 2018 10:02 pm
by radiowaz
I am in direct sampling, but in anything else, I hear nothing. when I run [email protected] I hear nothing on those freq or, and, pretty much nothing else on any other freq. (I'm still working on it). With HDSDR the bands are full and quality is excellent. but I can switch to sharp same freq and hear and see nothing. I don't know if the problem is with HDSDR or sharp or the idiot that is trying to use them..

Re: unknow radio stations on 27 mc

Posted: Fri Jul 06, 2018 7:31 pm
by W1ABA
You're hearing images, these types of receivers are very dirty, due to overload (causes non linear responses) and from the upconverter used in the tuner chip, which lacks proper rf filtering for the sum of the frequencies and the original frequency. Eliminate the tuner chip and use a high level mixer with proper filtering, and it would be a stellar performer.

1ABA