Eric, thank you for your concise explanation.
It is all clear now. According to his measurements his RX is the best
with and without preselector.
K3 comes the second best.
Preselector adds 12-13db of improved performance to K3. The strongest
impact by preselector is for IC7300 - the radio that have no roofing
filter because of it's architecture.
73, Igor UA9CDC
07.04.2018 23:33, Erik Basilier пишет:
Igor, are you saying that you could not view the numbers at his website? If
anyone has difficulty getting to the numbers, let me know and I can repeat them
here, but for now I will just refer you to the website again.
Here is a short url for that page:
Scroll down to the first handwritten table. The left-hand column lists the different radios tested. 3 columns to the
right shows test results for different pulse frequencies. Presumably, a higher pulse frequency means the interference
spectrum is more spread out around the wanted signal. However, this is not quantified or described in detail. Remember,
results of this test method are strongly dependent on the design of the pulse generator etc, so the if someone would
like to duplicate or compare to his numbers, they would have to duplicate his exact equipment, or come up with a new
similar test setup that could be regarded as a standard. For each radio, there are two rows of results (for each pulse
frequency). The first row represents the radio without preselector (but modified to add a roofing filter, except in the
case of the IC-7300). The second row represents the same radio with the addition of the preselector, which is his
personal design, also described at the website. If I am not mistaken, the preselector is entirely passive. All the
result numbers are negative dBm values. This means that a smaller negative number represents a stronger interference
signal that is in some sense tolerated. E.g. -20dBm is a great result, but -50dBm is a poor result. None of the numeric
results can be translated into, or compared with, numbers published by Sherwood or the ARRL. However, he makes a pretty
good case that his measurement method might be "better" than those conventional measurements in representing
the performance characteristics that are relevant in practical ham use under heavy interference from close-in strong
signals. For the ARRL or Sherwood to adopt his approach they would likely have to invest in additional test equipment
including custom-built items, and justify a standard method of doing this kind of testing, so I am not holding my
breath. The inclusion of the IC-7300 shows that the website content is not very old, but other than the K3 he has not
included any of the several radios on the market today that incorporate roofing filters as a standard part of the
design. Perhaps we could hope that some kind hams in Europe would lend him additional radios for testing with his
unique test equipment. As to his own conclusions, they should be covered by the text I already translated. Are any of
his statements (as translated) unclear? Remember, no real world radio has a "true" performance level even in
principle. Every time we look at performance numbers, they reflect imperfect concepts developed in our small human
minds, whether they are considered "standard" or not. A concept such as "better" is usually not an
objective way of describing things.
From: elecraft-boun...@mailman.qth.net <elecraft-boun...@mailman.qth.net> On
Behalf Of Igor Sokolov
Sent: Saturday, April 07, 2018 6:49 AM
Subject: Re: [Elecraft] OE3HKL's Measurements
Can you possible give a summary of the results of his measurements and
conclusions he has made?
73, Igor UA9CDC
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