[time-nuts] potential low-RFI power supply

[Dana Whitlow]

IIRC the HP3561A goes to 100 kHz.  It's a well-built FFT analyzer at heart.

Dana


On Sun, May 17, 2020 at 4:12 PM Taka Kamiya via time-nuts <
time-nuts at lists.febo.com> wrote:

> I have an HP audio FFT that starts from sub 1Hz so I can do that when I
> get mine.  What kind of load shall I use for this?  Purely resistive load?
> What kind of power?  Near 100%, 50% or??  I don't know off the top of head
> what the available RBW is.  It's HP3561A
>
> ---------------------------------------
> (Mr.) Taka Kamiya
> KB4EMF / ex JF2DKG
>
>
>     On Sunday, May 17, 2020, 4:12:03 PM EDT, jimlux <jimlux at earthlink.net>
> wrote:
>
>  On 5/17/20 11:53 AM, Eric Scace wrote:
> > Pro Audio Engineering announced a sale (through Friday) on its nominal
> 14 Vdc 4A switching supply <
> https://proaudioeng.com/products/pae-kx33-low-rfi-ac-power-supply/>. The
> test results <
> https://proaudioeng.com/products/pae-kx33-low-rfi-ac-power-supply/>
> webpage compares noise on the DC output and noise frequency spectrum under
> a variety of conditions with a lead-acid battery, an Astron linear supply,
> and a variety of switching supplies from other manufacturers.
> >
> > I have not used this and can’t vouch for its performance. Given recent
> discussions here on supplies, the analysis might be interesting. At least
> the supplier has attempted to quantify the performance of its power supply
> and make that information available to the prospective purchaser.
> >
> > It would be interesting to see comparable (or more suitable)
> measurements made by others posted here.
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>
>
> Interesting.. It would have been nice to see spectrum analyzer plots
> from, say, 0 to 1 MHz with a much narrower resolution BW.  1 MHz/div
> with 300 kHz RBW isn't going to show the "row of discrete spurs" that
> the switchers put out.
>
> 4mV ripple isn't bad, or at least, it's better than most of the other
> switchers.  The Astron linear is given as 5mV, but the scope photo
> doesn't seem to show anything. At 5ms for the whole screen, you should
> see some variation for over the 8.33 ms ripple period.
>
>
> I get that they're demonstrating the performance with a specific
> transceiver load - but I'd be interested in seeing measurements at zero,
> 50%, and 100% load on a switcher.
>
>
>
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