[time-nuts] Anybody want a Thunderbolt power supply

Charles Steinmetz csteinmetz at yandex.com
Thu Sep 1 07:34:08 EDT 2016

Mike wrote:

> I use the TAPR HPSDR LPU

I was unfamiliar with the LPU, so I took a look at the docs.  It 
develops several voltages, all from a +13.8v source.  This means that 
the -12v supply necessarily is a switching supply (to get the polarity 
reversal).  It is unfortunate that the power supply that needs to be 
quietest for a Tbolt to perform at its best is the one that will be the 
noisiest from this design.  (That will be true for any supply that uses 
nothing but a positive DC input.)

Speaking of noise, none of the datasheets for the four regulators used 
in the LPU gives any noise data.  It has always been my experience that 
if a manufacturer fails to provide a particular specification, it is 
because the part performs poorly in that respect -- so I presume the 
noise performance of all of the regulators in the LPU are mediocre at 
best for their type.

I have never measured an LPU, but all of the data available makes me 
think it is not a promising candidate if one wants the best performance 
from a Tbolt.

Best regards,


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