Hi Steve,
Not to throw cold water on this, but.... the original KSYN3 requires a ton of
firmware support, including a hand-tweaked table of thousands of PLL divider
values pre-calculated and stored in flash memory. We shoehorn the DDS reference
signal through a 3-kHz wide crystal filter in order to ensure no close-in
spurs, then adjust the PLL divider values in real time so there are no gaps in
the tuning range despite a nominal 20-kHz PLL step size. Lots of idiosyncratic
math, and a critical calibration step ("VCO CAL").
So if each of your repurposed KSYN3s comes with a K3 front panel MCU and flash,
no problem :)
73,
Wayne
N6KR
On Jun 24, 2015, at 7:18 PM, inventor61 . <invento...@gmail.com> wrote:
> I printed out the schematic of the original K3 synthesizer module. The
> diagram says 'rev. A4' and is dated 8 Jan 2010. Hope that's close to the
> as-built! (probably is)
>
> This gizmo appears to have an output range from 8.7 to 46 MHz. I don't
> know how much sauce it can develop but I have to imagine +10 dBm or so into
> 50 ohms, I bet it's flat across that range, and it looks like the thing
> would be whistle-clean.
>
> To get that, it needs a tight 49.38 MHz reference oscillator (I found a
> 0.5PPM TCXO for ~$30 from mainland China), and several common DC supply
> voltages.
>
> It also needs a small microcontroller or other way of providing the correct
> serial peripheral interface command lines and interaction. That processor
> would also control the output frequency, perhaps with an encoder, or
> whatever human interface might make sense….
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