[time-nuts] Thunderbolt spurs on 10MHz output at 100Hz and 200Hz from signal.

David C. Partridge david.partridge at perdrix.co.uk
Sun Sep 18 07:27:38 EDT 2016


Now that's interesting I just re-ran the measurement, and got a quite different result which is attached.  The spurs have GONE.

My only guess right now is that the E4406A power supply is getting quieter as it has been on for longer (I've only had it powered for short periods before now).

Dave

-----Original Message-----
From: time-nuts [mailto:time-nuts-bounces at febo.com] On Behalf Of Magnus Danielson
Sent: 18 September 2016 11:56
To: time-nuts at febo.com
Cc: magnus at rubidium.se
Subject: Re: [time-nuts] Thunderbolt spurs on 10MHz output at 100Hz and 200Hz from signal.

Hi,

On 09/18/2016 12:26 PM, David C. Partridge wrote:
> The local power is 50Hz, so I can understand the 100Hz spurs, but I 
> don't quite "get" where the 200Hz spurs are coming from.  Or is that 
> just BAU harmonics?

Consider full-wave rectification of 50 Hz, the power consumption load on the capacitor after the rectifier creates an inverse sawtooth wave of
100 Hz, and sawtooth waveshape have both even and odd harmonics.

While much of this is regulated out in the next step, some of it makes it though.

Cheers,
Magnus

>
>
> Thanks
>
> Dave
>
>
>
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