[Elecraft] New KSYN3AUPG Installation

[Wayne Burdick]

Hi Mike,

I'm glad this went well. 

Another customer who just did the installation tested transmit close-in phase noise before/after and saw pretty dramatic results. At +/- 0.5 kHz from the carrier, the new synth was down about -133 dBc, while the old was down about -115 dBc. (This reduction in noise will provide a substantial benefit in both RX and TX, especially if the other radios you're tuned close to are also using K3s with the new synths.) 

As you move farther from the carrier the results become less dramatic, with the old and new intersecting in their noise floors somewhere between 5 and 10 kHz. The original synth was no slouch, but the new one takes things to an entirely new level.

Two customers have now captured CW keying waveforms from the old and new synths, demonstrating a very significant reduction in timing jitter.

Finally, one of my techs called me this morning wondering if we had improved tuning accuracy. The answer is yes--we just forgot to tell them. The new synth has a lot less quantization error in its tuning, so even on the highest bands, VFO fine-tuning increments are very close to 1 Hz.

73,
Wayne
N6KR


On Feb 20, 2015, at 3:26 PM, Mike Cox <mike at ab9v.us> wrote:

> I installed the new K3 synthesizer boards last night into s/n 398 (with sub Rx). The installation was very easy, requiring only the removal of the top cover and the old synthesizer boards. I didn't even remove the rig from the operating table, electing to sit my anti-static mat in front of the radio and wearing the grounding strap. The radio remained connected with +12 power turned off (it would have taken me more time to rewire the radio into the station than was required for the actual board swap). Total installation time was about a half hour.
> 
> The radio powered up without incident and is performing as it should. Config: VCO MD is still present but only displays "--" as it is no longer needed to align the synthesizers.
> 
> As one would expect, there is initially no obvious difference in the before/after modification as far as the function of the radio. It "sounds" the same as before. Since I only have one K3, I can't do a quick-change A/B comparison of before and after. I'm not set up to perform the types of measurements required to accurately measure the changes regarding phase noise. I'll just have to take the word of others that the radio is now able to perform at a better level than before. I may be able to tell an improvement in CW keying timing at 35+ wpm but it may be my imagination. It does sound good! Here's where performing a before/after test would have real meaning to me.
> 
> But once again, I'm able to update my old K3 with the latest changes and make it function as a new radio. I didn't have to buy a whole new radio! That's pretty neat! I've saved so much money over the past years (not having to buy a new radio) that I probably should go out and buy a second K3. Maybe if Wayne would give me a hat...
> 
> I'm going to be operating for a while in the ARRL CW DX contest this weekend so I'll give it a practical test. From my perspective there's probably no compelling reason to make the synthesizer swap but in theory, it should be an even quieter transmitter with regard to phase noise and the cw keying may be a bit cleaner with reduced lock-up time on the synthesizers. It's an easy board swap!
> 
> 73,
> Mike, AB9V
> 
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