At the W1KM contesting site, we routinely see signals of +5 dBm or louder on/near 40m from SWBC stations (using a single Yagi). We also have two modest-power local AM stations (1 to 5 kW, a few miles away) just below 1500 kHz that show up even a bit stronger than that on our 160m antennas.
Without taking into consideration signals from our own multi-multi transmitters, a receiver is already faced with >>130 dB range between weak signals on 160m in mid-afternoon arriving from Europe and these other signal sources. WD3Q, a contester in Washington DC, has much stronger AM BC stations to deal with, including a 50 kW station on 1500 kHz. Wide-open receiver front ends attached to an A/D converter are not yet viable for these locations. -- Eric K3NA on 09 Feb 24 20:44 N8LP said the following: > You may be right, Al. I think the improvements may be incremental, and > distributed among various aspects of the design, not just the ADC. For > instance, ultra-low jitter clock sources, faster FPGAs with improved IP > cores, etc. I think most hams would be thrilled with an improvement to 130dB > BDR, along with getting rid of phase distortion, ringing and other anomalies > in the xtal filters and other analog components. Unless you live near a > shortwave broadcast station, or have a high power ham nearby on the same > band, you're not likely to need 130dB BDR anyway. Even in those cases, > having 200dB BDR probably wouldn't help unless there is a LOT of improvement > in transmitter spurious emissions, distortion and phase noise. > > The highest signals I have seen here, during Field Day when there were > several stations operating within a few miles of me, were <120dB above the > noise floor. Of course, it's very important not to use any more front end > gain than necessary for the band/conditions. > > 73, > Larry N8LP > > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
