[Elecraft] K3 receiver desensing on CW during contest

[Eric Scace K3NA]

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
>   
>