[Elecraft] A datapoint comparing old vs new synthesizer boards.

[Dave Olean]

I recently got a new K3 and it was one of the first units supplied with the new and improved synthesizer board. In reading a few comments on the reflector, a number of people wanted to know if anyone could detect any difference between the old and the new. I also have some older K3s and decided to compare one of them head to head with the new one on ten meter CW using a 500 Hz bandwidth and check for MDS. I used the line out jack and an HP AC VTVM and 8640B signal generator. Here is what I found:
K3 #8858   no preamp    -137 dBm   new synthesizer board
                preamp ON  -139 dBm     new synthesizer board
K3 #1504  no preamp     -134.5 dBm  old synthesizer board
                preamp ON   -137  dBm   old synthesizer board

I also ordered a pair of synth boards for one of my old K3s on March 1, but it will be awhile before it gets here I guess. I ordered a P3 kit with it and included comments that I was in no rush for the P3 so ship it all together. From the comments I have seen on how many have been ordered, I might be waiting a long time for the P3!!  At my age, I'll probably forget about the order in another week or so. When it shows up, I'll wonder what it is and who ordered it!!  The plan is to put new synth boards into #1504 and then I can check MDS again to see how it looks. From my checking, it looks like the newer K3 is almost 3 dB better than the older one at least as far as minimum discernable signals go.  The new board definitely makes a difference, and my result tracks reasonably well with what what others have found.

Dave K1WHS