[time-nuts] PCB layout question for GPSDO (Tobias Pluess)

[John]

On 31/1/20 7:18 am, time-nuts-request at lists.febo.com wrote:
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> ------------------------------
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> Message: 8
> Date: Thu, 30 Jan 2020 20:20:08 +0000
> From: Tobias Pluess <tobias.pluess at xwmail.ch>
>
> b) would you worry about the switching regulators? I know linear would be better, but the professional GPSDOs also have switchers, and besides that a linear regulator would not be so nice because my power supply will be at least 15 volts.
>
> c) is the usage of a RS232 chip a good idea or would you kick that out because they produce such massive amounts of EMI that it will disturb my GPS module or OCXO?
>
Keeping a switching regulator quiet is a world (rabbit hole) all of its 
own. This can be magnetic as much as electrical, so requires both 
electrical and magnetic shielding. I believe there are quiet modules on 
the market, but am not across them these days. Quiet here is a relative 
term.

There has been comment about even the low power RS232 +5 to -5 
converters (MAX232 & such) being noisy for an RF environment.

John