[time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

Bruce Griffiths bruce.griffiths at xtra.co.nz
Thu Dec 17 22:20:37 EST 2015


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 <phk at phk.freebsd.dk> wrote:
 

 --------
In message <CAPnVNRVsvdM+xb6rove8zU4sR1RjBLe+tahWcVyDNcWPhPWiMQ at 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
phk at 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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