Two additions to my recent posting based on several replies.
The ARRL composite transmit noise test measurements have been 7.5 dB lower
than reality for many years. This is true for all radios, not just the K2.
My comment about improving the phase noise only applies if the RF board is
re-designed. I don't think it is possible to significantly reduce the phase
noise with a mod on the current board.
-John
KI6WX
Peter;
I have posted on the web a detailed set of measurements of the K2 phase
noise, both in receive and transmit. The measurements cover a frequency
range of 20 Hz to 45 kHz. These measurements can be viewed at:
http://home.pacbell.net/johngreb/k2phasenoise.pdf
The ARRL composite transmit noise measurements that were published in QST
are in errror and show less noise than reality. The transmit phase noise
measurements in the above document are the correct phase noise
measurements, but they do not include any amplitude noise that might be on
the transmit carrier.
The K2 oscillator phase noise is good for a simple low-current
synthesizer, but there are ways to make it better. I note some of those
in the above document. A re-designed K2 RF board could drop the phase
noise by at least 10 dB, which would improve the 5 kHz two-tone
third-order dynamic range 6 dB.
-John
KI6WX
Maybe not the cleverest question of the year but I cannot resolve this
one
myself and I'm eager to understand.
It is said that the synthesized LO of the K2 is of a unique design.
Though, when I compare the LO phase noise specs of the K2 and the
AOR7030,
the latter seems to show much better specs.
What makes the K2 synthesizer so special ?
I'd appreciate any comment.
Peter, PE1E
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