[time-nuts] HP 105B power supply noise

[ewkehren at aol.com]

Hi 
Could the transformer hum add some noise? Vibration?
Bert






-----Original Message-----
From: Bob Camp <lists at rtty.us>
To: 'Discussion of precise time and frequency measurement' <time-nuts at febo.com>
Sent: Thu, Feb 25, 2010 12:33 pm
Subject: Re: [time-nuts] HP 105B power supply noise


Hi
Sounds like the biggest thing you need is better ripple rejection. 
Without looking at the 105B schematic, I would guess it's going to have some
ard to find parts on it. If the board it's self is butchered that would
lso be an issue. I'd vote for a modern replacement. 
Bob
-----Original Message-----
rom: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
ehalf Of Ralph Devoe
ent: Thursday, February 25, 2010 12:06 PM
o: time-nuts at febo.com
ubject: [time-nuts] HP 105B power supply noise
Speaking of low-noise regulators, I have an HP 105B standard that has
 burned up regulator board. The previous owner patched it up but it
till has about 50 mV of 60 Hz on the regulated 18.7 volt line. The 5
Hz output has a half a dozen 120 Hz noise sidebands when viewed on a
pectrum analyzer (an HP 3585a).
I'm trying to decide whether to repair the board or put in a modern
egulator. I'm assuming that I need better than 1 mV stability and
uch less noise to get a clean signal. Any suggestions?
Ralph
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