[time-nuts] Normal operating specs of a Morion MV89?
scott.j.stobbe at gmail.com
Wed Sep 28 12:38:29 EDT 2016
Your oscilloscope fft is plotting single-side amplitude spectrum in V/rtHz
(dBV/rtHz), this is in contrast to a spectrum analyzer which plots power
spectral density W/Hz or (dBm/Hz).
So -2.17 dBv is 10^(-2.17/20) = 0.779 Vrms comparing this to your Vpk-pk
2.3 / 2 / sqrt(2) = 0.813 Vrms
That's not to say a scope can't plot power spectrum if the load is
explicitly given or assumed 50 Ohms, but in general the plot is amplitude.
On Wed, Sep 28, 2016 at 1:38 AM, Tim Lister <listertim at gmail.com> wrote:
> On Tue, Sep 20, 2016 at 12:56 PM, Bryan _ <bpl521 at outlook.com> wrote:
> > May also want to check the output amplitude. If memory serves me correct
> it is very common for a capacitor inside this model number to fail. It can
> be fixed but requires a torch or a pretty heavy duty soldering iron to get
> the can open.
> > http://www.rbarrios.com/projects/MV89A/
> > -=Bryan=-
> I managed to borrow a Tek TDS 2024B 200 MHz scope from work and hooked
> it up to the output of my MV89A. I get a peak-to-peak measurement of
> 2.3 V which if I have converted it right is ~11 dBm ? Alternatively if
> I turn on the FFT mode on the scope I get a peak value of -2.17 db if
> I am driving the cursor mode correctly. With the 10 MHz from the
> radioshackus GPSDO used for triggering, it takes ~18 seconds for the
> MV89 waveform to drift 1 cycle (this is without anything connected on
> the Uin or Uref pins).
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