[Elecraft] K-1 Sensitivity

[James R. Duffey]

The advent of inexpensive, low noise solid state devices, coupled with good
design practices mean that receiver sensitivity on the HF bands is no longer
a problem. Most, if not all, of the rigs sold within the last 20 years are
limited by the atmospheric and locally generated noise at a given location,
not the receiver sensitivity.

On 40 M as an example, the lowest amospheric noise one can expect is about
0.22 microvolts at the antenna in a 300 kHz bandwidth. This would correspond
to a very quiet rural location with no manmade noise present during a time
of no solar or geomagnetic disturbances. Not th e typical site for most of
us. A typical urban location is about 1 microvolt under the same conditions,
but with man made noise is usually much worse. These numbers are roughly
halved at 20 M.
 
Almost all of the modern receivers have sensitivities of 0.1 micrtovolts or
better in this bandwidth. And much of that sensitivity is wasted. Your
measurements were probably limited by external noise sources, not by the
sensitivity rigs you were comparing. On HF in these days, sensitivity is an
overrated parameter by which to judge a receiver. - Dr. Megacycle KK6MC/5
-- 
James R. Duffey KK6MC/5
Cedar Crest, NM   DM65