NQ5T:
>It's what makes me think the variety of opinions on what floats our
respective boats (or not) is based on something besides actual performance.
Which is why I set out to make some measurements. And even though there were
some issues with the first attempts at it (right approach, but the wrong
meter, whatever), that will be fixed for the next round.
Exactly Grant, which is why I pay little
attention to opinions on eHam or elsewhere. As
someone once said, opinions are like ***holes...
we all have one. Valid test measurements such
as those ARRL/RSGB/Sherwood/W8JI provide are very
helpful to sort fact from fiction (or opinion as
the case may be).
I still chuckle at a very well-known Icom
"guru" who, when asked if the Pro 3 was better than
the Pro 2, said close-in IMD and BDR was "much better".
ARRL measurements below show only 1 dB better IMD and BDR
at 5 kHz spacings! ;-) I'm sure this small difference
is undetectable by ear and is probably within the test
measurement error. For some reason he never posted my
response to his 756 list pointing out the discrepancy
in his ears and ARRL measurements...a classic case of
"Hear no evil" syndrome (which seems to be a common
affliction on his Icom webpage also).
http://www.elecraft.com/K2_perf.htm#Main%20RX%20Table
This is why measurements are so helpful to sort fact
from opinion, and thanks for attempting the measurement!
BTW we went through this in the Beta group when
one tester felt S/N (i.e. MDS) was better in a V2
beta compared to V1. I challenged someone to prove it
with measurements and below is the result (BTW the
Fluke 8060 *does* measure True RMS). Audio levels,
S-meters, etc can fool us humans but they will not
fool properly made measurements.
73, Bill W4ZV
"I've completed the exercise comparing MDS between 1.373b5 and 2.034xt.
In each case the firmware was freshly loaded, full resets
were carried out and thereafter the only adjustments made were:
AGC off
Step 10 Hz
Band 40m
Mode CW
B/W 500 Hz
frequency 7040.340 kHz
MDS was determined using a Elecraft XG1 (Output
assumed to be 50uV into 50 ohms or -73dBm)
Kay Elemetrics 5150 0-80dB step attenuator.
Fluke 8060A 100 kHz b/w RMS voltmeter.
Orion speaker output terminated in 8 ohm resistive load
Audio monitored with Hi Z monitor amp.
And the answer is.................
1.373b5 -129 dBm +/- 2 dB
2.034xt -129 dBm +/- 2 dB
Each unit was checked 3 times. +/- 2 dB was the spread.
In conclusion I can detect no difference in MDS between
these firmware versions. Though I did notice the S-meter
is more stingy by about 6 dB with 2.034xt.
73
Bob, 5B4AGN"
_______________________________________________
TenTec mailing list
TenTec@contesting.com
http://lists.contesting.com/mailman/listinfo/tentec
|