[time-nuts] Low noise power supplies?

[Burt I. Weiner]

Bob,

I have a pair of HP-3551A's*.  I'm very familiar with making 
transmission lines measurements, and it seems that measuring power 
supply noise would be the same, except that you want to block the DC 
from the input of the instrument.  What has your procedure been and 
what numbers have you come up with?  Since these instruments read in 
dBm0, do you reference from the supply's voltage and then convert to 
mV (difference)?

* One that I picked up off eBay for $75.00 looks new and came with 
the complete manual, and the battery will run it most of the day.

Thanks,

Burt, K6OQK


>Subject: Re: [time-nuts] Low noise power supplies?
>
>A non-standard but repeatable way to measure power supply noise is 
>to use a Transmission Impairment Measuring Set (TIMS) such as the 
>HP3945(6)A or 3551
>(2)A. These were intended for use in pairs to assess analog 
>telephone lines for data use. As well as an AF generator, frequency 
>counter, amplifier, monitor speaker and level meter they will 
>measure broadband noise. Being designed for POTS they will also 
>withstand at least 50V DC at the input while measuring the noise. 
>You can also apply internal filters if required. The last digit 
>designates a North American? (BELL) or European (CCITT) standard 
>unit, but broadband noise is the same. They can be picked up really 
>cheaply now (list was$3000-$5000) and make a nice compact audio test set.
>
>Robert G8RPI.
>
>
>

Burt I. Weiner Associates
Broadcast Technical Services
Glendale, California  U.S.A.
biwa at att.net
www.biwa.cc
K6OQK