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:
https://tinyurl.com/ycn9kbss
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.

73,
Erik K7TV

-----Original Message-----
From: elecraft-boun...@mailman.qth.net <elecraft-boun...@mailman.qth.net> On 
Behalf Of Igor Sokolov
Sent: Saturday, April 07, 2018 6:49 AM
To: elecraft@mailman.qth.net
Subject: Re: [Elecraft] OE3HKL's Measurements

Eric,

Can you possible give a summary of the results of his measurements and 
conclusions he has made?

73, Igor UA9CDC







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