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, Charles _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
