The problem described below also exists in KX3,
That is why I always adjust bandwidth to 50,150,250, 350 etc Hz.
73, Igor UA9CDC
01.08.2017 16:25, John Reilly пишет:
Here are the odd details on the KX2 filter leakage. If the filter
bandwidth is 500, 400, 300, 200 or 100 Hz, filter leakage makes the
measurement at 2 kHz impossible. On the other hand, if the filter
bandwidth is 550, 450, 350, 250, 150 or 50 Hz, then the measurement
can be made. The League chose to publish a 2-kHz dynamic range in QST
even though the measurement cannot be made on the high side with the
standardized 500-Hz filter bandwidth (or any even bandwidth value).
Note: Both the League and I only publish the LOWER of the two
measurements. Let’s say the low side dynamic range of some radio is
95 dB and the high side is 90 dB. Both the League and I publish the
lower worse-case 90 dB number. In the case of the KX2, I couldn’t pick
the lower of the two readings since no measurement is possible when
using the standard 500-Hz filter.
Since the 2-kHz dynamic range value could not be made with the
standard filter bandwidth at 2 kHz, but could be made at a 3-kHz
signal spacing, I published that data. It may be of interest that the
2-kHz dynamic range number with the non-standard 450-Hz bandwidth was
only 1 dB worse than the 3-kHz value. The point of listing the 3-kHz
value, or any other radio with a non-2 kHz listing is to point out the
radio has a limitation in its filter performance.
My long form report on the KX2, available in PDF format, goes into
detail about this issue, and has data on the two radios I tested,
listed by serial number.
At this point, Elecraft does not know why the KX2 behaves this way, or
whether there is a possible firmware fix.
Rob Sherwood
NC0B
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