Al, From the tests I have done, I discovered that the K3 has a flat passband and very sharp filter skirts - in fact, very close to the "ideal" filter sought by many in past years. Other receivers tested (K2, Yaesu FT-900, FT-817) showed that their passband was not flat, but tapered smoothly to a lower response at higher audio frequencies.
The K3 is very much quieter out of the passband than other receivers (the K2 is close) - the response is down at least 60 dB as opposed to the out of passband 'garbage' in other receivers only about 30 dB down. So my supposition is that we are not accustomed to hearing an "ideal" filter response - we are accustomed to hearing that tapered response, and as a result the K3 is judged to be "noisy", when in fact, it is very quiet for out of passband response and is faithfully reproducing the in-passband response that is actually present. We may not like to hear what is actually present, but in my mind, the K3 is faithful in re-producing it without distortion - that in my mind is the definition of a High Fidelity receiver. 73, Don W3FPR Al Lorona wrote: > Hi, Everybody, > > What great comments I got from you in private e-mail messages. It's highly > interesting getting your perspectives on receivers and listening. > > Due to day job and family I can't respond to every observation and objection > but in particular Doug KR2Q-- who has some of the best ears in ham radio-- > did tell me something I had already thought about which was that it might be > better to record a signal instead of just noise. Let me tell you why I chose > not to do that, at least for this first run of the test. > > Sticking with a signal-free CW passband allowed me to keep the test as equal > as possible between the receivers. I was able to set the record levels within > about 1 dB, and since noise isn't affected by QSB making all of the > recordings on the same frequency in a period of a few minutes helped to > equalize the test as well. In other words I came as close as I could to > simultaneously recording the same thing on all three receivers. Most > importantly, I was hoping to hear from those folks who can hear tones, > digital artifacts, and other noise up around 10 kHz which is what started > this whole "noisy K3" thread in the first place, and we certainly don't need > a signal present to do that. In short, this was not a real-world test, it was > a contrived laboratory test to listen for one specific thing (noises) > independent of any signals. On purpose. > > Remember, the whole point of this is, given that the K3 has measurable noises > that irritate many operators, we would like to find out if in a double-blind > type of test whether these noises are significant enough to enable a positive > identification, without looking at a spectrum analyzer, without > post-processing the audio, without making any other measurements, just by > trusting what your ears are telling you. So if you want to play, no > performance-enhancing substances are allowed. :^) Many folks can identify a > Chevy 350 engine or a Stradivarius violin while blindfolded because they hear > a unique signature in those sounds. Could the same be true of a K3? > > These tests will tell us if the high frequency digital artifacts that many > claim to hear are the fingerprint that betray a K3. We'll run another test > very shortly. Please stay tuned. I hope you think this is fun. > > Regards, > > Al W6LX > > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
