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
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