Also add
1) BNX002
(attenuates noise in 1MHz to 1GHZ region) between the dc input and the input to:
2) Simple LCR filter - attenuates from 10kHz to 10MHz (see attachment)
Output of which is connected to the regulator input.
3) Like all the so called RF regulators with internal low pass filters your
regulator is exceptionally noisy at low frequencies.
Try substituting something else - a good one should be at least 20dB quieter at
low frequencies
4) Change the input amplifier to something like that depicted in 2nd
attachment. Reduces complexity and effect of residual power supply noise.
Reduce feedback resistor values.
Bruce
On Friday, 18 December 2015 12:08 PM, Poul-Henning Kamp
<p...@phk.freebsd.dk> wrote:
--------
In message
<capnvnrvsvdm+xb6rove8zu4sr1rjble+tahwcvydncwphpw...@mail.gmail.com>, Anders
Wallin writes:
>My 'ultra-low-noise DC-supply' in the form of a lead-acid battery improves
>things somewhat, but some spurs still remain:
>http://www.anderswallin.net/wp-content/uploads/2015/12/2015-12-17_fda_spurs_and_comments.png
>interpretations and explanations are welcome!
>The board was not enclosed in a metal can for these tests.
Isn't that the explanation ?
Any SMPS in the vicinity is going to show up...
--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
p...@freebsd.org | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
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