what about using a 25megs tcxo??? )finetune with a trimmer or
with an analog voltage from arduino??)
way way lower drift then ... as an example i use 0.2ppm tcxo when
modding lnb for qo100 ... similar could be used on raduino ...
not??
not 50ppm ... not 20ppm ... 0.2ppm
greetz sigi dg9bfc
Am 17.05.2021 um 22:34 schrieb Jerry
Gaffke via groups.io:
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You're right, 10pf is the max value, not 8pf.
Probably best to set it to 10pf.
My understanding is that the load capacitance setting has nothing
much to do with startup drift.
Only with the final parallel resonant frequency when the crystal
is placed in a circuit.
These crystals are intended for a circuit with more parallel
capacitance than we have,
so in our circuit it operates at about 25.150mhz instead of
25.000mhz.
But that's ok, it gets calibrated out.
Setting it for the minimum capacitance value of 5pF would cause it
to operate at an even?
higher frequency.??
I would like to know if I am wrong about this startup drift thing.
Jerry, KE7ER
On Mon, May 17, 2021 at 02:54 PM, Jim Sheldon wrote:
Thanks Jerry,
You beat me to the explanation. ?The OP mentioned a menu
routine we (TSW) had in some of our early firmware but we
removed it after we discovered it essentially made no
difference. ?We just set it to a compromise 10pF and left it
there. ?
?
Start up drift is so minimal it isn¡¯t even worth spending
time messing with it.
?
Jim, W0EB
TSW Project Coordinator
