Measurements and conclusion
Contents
We put the Mutec REF10 Nano in the new RF-blocking measurement box and then hooked it up to the Wavecrest. After an hour of warming up both the Wavecrest and the REF10 Nano, we took some measurements.
We measured with both the internal power supply and an external lab power supply (15 volts). The differences are minimal, but visible. With a very quiet linear power supply, the results might be even slightly better. However, assume that the power supply must be very quiet and stable to achieve a serious improvement. A ‘normal’ linear power supply will not bring you anything, except a bank transfer to the retailer.
We can be brief: the Mutec REF10 Nano measures very well! Only 28ps total jitter is incredibly low. Realise that this is all jitter combined: deterministic and random. (Random jitter has a more unpredictable character and is more difficult for a manufacturer to deal with. Deterministic jitter is mainly caused by identifiable sources of interference and is probably easier to tackle).
Average (1-Sigma) jitter at 2ps – that is the noise floor of the Wavecrest – and peak to peak in the femto-seconds shows how stable the REF10 does its job. We have the feeling we are at the limits of the Wavecrest here. (NB: we didn’t have the Aeroflex at the time of review).
What we see in the measurements – even with the lab power supply – is a minimal amount of noise from the switching power supply and some regulators (we think). On both phase noise and low-frequency modulation, we see some peaks (we’re talking femtoseconds…!). Especially short around the 10 MHz pulse. In this price range no shame of course. If you want to get rid of that, there is still the “regular” REF10 or the REF10-120 of course.
All in all, a very good result. Top notch work.
On the MC3 / Word Clock out
We were curious though if we could measure differences on the word-clock output of the Mutec MC3+. We unfortunately do not have the option on our Wavecrest to directly use a spdif signal, from which the Wavecrest then extracts and analyzes the clock. (You can’t have everything). But maybe we can do that with the Tektronix TDS7104 scope that is on the way.
We definitely see an improvement in terms of phase-noise when using the REF10. It drops by 4dB from -86dBc/Hz to -90dBc/Hz. And the overall picture is more calm. Certainly very close to the clock is significantly improved. And that’s a crucial area.
Overall, however, we see no decrease in jitter. The histogram measurement is practically the same. But that may be because the wordclock doesn’t really benefit from the REF10…. although Mutec itself says that it should be better. But as said: phase noise improves significantly. And that is certainly audible.
