[DSP-10] Grounding of X101 case (10 Mhz xtal), grounding of mixer U3 / U15

[Marius Hauki]

Hi list,

in my kit there was a thin cylindrical cased 10 MHz crystal instead
of the traditional case.
I found this to be a little "unstable" mechanically if mounted
on top of the board without support. I soldered it below the board instead. 
I soldered the case of the crystal to the groundplane to
avoid microphonics when operating portable from my car with the engine 
running in the winter to keep warm.
I guess there will be some more stray capacitance to ground because
of this because the xtal leads now have a closer path to ground to
set up an electrical field in the air dielectricum . Do anybody have 
experience with this mounting form ? Do you have experience if it will  
affect the stability of the xtal osc in a any way ?
(I plan to use a portable GPS diciplined TCVCXO external reference later for 
some low power EME experiments so this will be a temporary arrangement).

Mixers :
========
I saw that the RX sensitivity could be affected if U15 was not grounded 
properly on Bob's page. I took some copper litz and soldered the case to 
ground as suggested. While I was at it, I also grounded U3 (the first mixer) 
the same way. Do anybody have objections to help U3 with grounding as well ?

73 de LA9EEA







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