[time-nuts] AC line distortion [Was: HP 105B Battery, the saga continues]
scott.j.stobbe at gmail.com
Tue Oct 4 09:26:31 EDT 2016
Considering some signal generators will have 1% (-40dBc) distortion with a
5k - 10k price tag, your 1% is not to bad.
On Mon, Oct 3, 2016 at 8:52 PM, Jeremy Nichols <jn6wfo at gmail.com> wrote:
> As an experiment, I bought an AIMS sine-wave inverter for the 105B Quartz
> Oscillator. The inverter has a built-in transfer switch that is supposed to
> allow the load to operate from the AC line and automatically switch to
> battery/inverter should the AC power line fail.
> In fact the thing seems to work—the output is a nice 118 VAC sine wave
> measuring 60.189 ± 0.003 Hz and the transfer switch is fast enough that the
> 105B doesn't seem to notice the change. The "AC Interruption" light doesn't
> light and I don't see a flicker of the 5 MHz output on my scope.
> Just for the fun of it, I connected a filament transformer and ran the low
> voltage into my distortion analyzer. The result was about 5% distortion for
> the inverter and 1.5% for the AC line. This got me to wondering, we've
> discussed the AC power line frequency at length but not other "qualities"
> of that "signal.' I was surprised that the AC line had so much distortion
> but it's a subject I've never considered. Has anyone in this group looked
> at this? [Yes, this is perilously close to not being appropriate Time-Nuts
> discussion matter—sorry!]
> On 9/18/2016 4:33 AM, Scott McGrath wrote:
>> That NiCad pack is part of the power supply and as Jeremy points out is
>> part of the filter system. And so one needs to restore it as part of the
>> instrument as even the 28V external power supply floats these cells and
>> trips power interruption indicator if lost
>> Power supply is not terribly hard to fix and the small signal transistors
>> can be replaced with 2N 2222,3904 and 3906'es depending on rating. You
>> don't even need a extender a Huntron tracker or similar current limited
>> lissajous bridge will identify failed or leaky caps and semiconductors
>> Remember HP did nothing without a good engineering reason and that plate
>> is there for RF shielding to prevent stray sources coupling with the outputs
>> If a proper rebuild is too expensive I'd suggest selling it on the well
>> known auction site rather than hacking it up as 105's have been selling in
>> the hundreds regardless of condition
>> On Sep 17, 2016, at 10:16 PM, Jeremy Nichols <jn6wfo at gmail.com> wrote:
>>> How did you come up with the 33,000 uF number, Perry, and is it one big
>>> capacitor or lots of little ones tied together? The big cap will also
>>> filter out some of the remaining ripple in the power supply that may have
>>> been managed by the ni-cad battery.
>>> On 9/17/2016 3:50 PM, Perry Sandeen via time-nuts wrote:
>>>> Where the nicad pack was located one can put in 33,000 uF of Nichicon
>>>> 105C caps for $20 for a buffer hold over. <snip>
>>> time-nuts mailing list -- time-nuts at febo.com
>>> To unsubscribe, go to https://www.febo.com/cgi-bin/m
>>> and follow the instructions there.
>> time-nuts mailing list -- time-nuts at febo.com
>> To unsubscribe, go to https://www.febo.com/cgi-bin/m
>> and follow the instructions there.
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/m
> and follow the instructions there.
More information about the time-nuts