[Elecraft] Update to KSYN3A FAQ (some measured dynamic range numbers)

[Joe Subich, W4TV]

On 2015-02-13 10:08 PM, Chortek Bob via Elecraft wrote:
> The new synthesizer has essential the SAME IMDDR 106 or 103
> depending  on the filter bandwidth.

Incorrect!  You are comparing measurements by different labs with
different test equipment and procedures.

Sherwood measured 104 dB w/200 Hz filter and 96 dB w/400 Hz filter
for the old Synth vs. 106 and 103 for new synth.  That's 2 to 7 dB
improvement depending on filter bandwidth.  Since the synthesizer
is about 6dBc/Hz better than the old synthesizer, the first order
estimation is that the improvement in narrow spaced IMDDR3 is due
to the decrease in phase noise.

> So, my question:   is the real import of all this that the new
> synthesizer will give the K3 an IMDDR which is NOT limited to 86
> dbs by Reciprocal Mixing so we will now get the FULL benefit of a
> IMDDR of 106/103?If so, that 20 db improvement is huge.

One would need to look into the way in which ARRL measures Reciprocal
Mixing to understand exactly what that "Spec" is telling you and what
improvement one might find.  It is safe to expect the reduction in
phase noise to directly impact both narrow spaced IMDDR3 and Reciprocal
Mixing.

BTW, I just reviewed the original ARRL review of the K3 (April 2008) and 
their Reciprocal Mixing numbers were -116 dBc @20 KHz, -106 dBc
@ 5 KHz and -95dBc at 2 KHz.  That's a far ways from -89 dB that you
quote.  Assuming a 6 dBc/Hz noise improvement in the new synthesizer,
you can make the numbers -122, -112, -101 which would be a significant
improvement.

73,

   ... Joe, W4TV