Wayne,
Nice workaround for the lack of ”pin-1” .
It seems to offer:
Applicable on all XO:s
Inexpensive
No impact on present XO specification (phase noise etc).
Holdover without EXT REF
Function check by watching REF CAL
Thoughts:
1. The ref oscillator is not actually locked in the above solution.
You have talked of an add-on board for the K144XV which will among other
things contain a PLL locked to KREF3.
There will not be an optimum accuracy between the IF:s unless the K144XV
PLL is designed to lock to the EXT REF instead.
Then there must be a function for holdover in K144XV also.
2. Someone suggested use of a GPS 1pps ext ref. That is useful if the
REF-lock module MCU can perform some averaging over a longer period since
the 1 pps is only accurate to 1ppm (typically).
Questions:
1. What is the minimum PN , spurious and harmonic requirement for the
Elecraft TCXO?
I have been trying a prototype using AD4001, a VC-TCXO and an Atmel
Tiny.
It is locked to an external GPS derived 10 MHz. Probably this solution
has higher PN than the Elecraft TCXO.
I am also investigating if a Slilicon Labs Si 550 is usable in this PLL.
2. Are you going to publish the K144XV schematic?
73
Jan
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