[time-nuts] Power supply for Thunderbolt

Dave Brown tractorb at ihug.co.nz
Sun Aug 10 01:30:34 EDT 2008

----- Original Message ----- 
From: "John Miles" <jmiles at pop.net>
To: "Discussion of precise time and frequency measurement" 
<time-nuts at febo.com>
Sent: Friday, August 08, 2008 1:21 AM
Subject: Re: [time-nuts] Power supply for Thunderbolt

>>  It would be interesting to see how the 'red panel' Thunderbolts 
>> (the
>> packaged type that run from an included switching supply fed from 
>> 24
>> VDC) perform under a test regime such as that TVB used to compare
>> various three rail power supplies.  In 'distant past' posts, maybe 
>> 18
>> months back, it was suggested that this supply is a particularly 
>> good
>> performer, but IIRC no data was supplied to support this statement.
>> Anyone able to oblige?
> This (cluttered) graph is indicative of the results I've seen.  The 
> Lucent
> supply used in the older red-and-black labelled Thunderbolts was not 
> very
> clean, and its proximity and orientation adjacent to the 
> Thunderbolt's PCB
> didn't help.
> Red = the new ("TAPR") Thunderbolt with my old Thunderbolt's Lucent 
> supply
> Blue = the old Thunderbolt with its Lucent supply
> Orange = the new Thunderbolt with the supply Tom chose
> Purple = the old Thunderbolt with Tom's supply
> The reference for the red trace was somewhat noisier below 100 Hz 
> than the
> one used for the others.  You should assume that the red trace 
> coincides
> with the orange one below 100 Hz.
> -- john, KE5FX

Tnx John-looks like the included power supply was not a great 
performer in this regard.
DaveB, NZ 

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