[Test-Equipment] HP 8656A question

[Gary Chatters]

On Mon, 21 Jul 2003, Carl Walker wrote:

> On Monday 21 July 2003 20:27, Gary Chatters wrote:
> > From the specifications in the catalog
> >
> > Residual FM:  < 30 Hz RMS  where:
> > Frequency Range: 0.1 - 123.5 MHz
> > Post Detection Noise Bandwidth: 0.05 - 15 kHz
> >
> > This taken from a table for various bandwidths and frequency range.  This
> > seemed to be the entry that applied to you.  It was the highest value.
> > Maybe what you're seeing is not far from spec.
>
> It seems as if it's not unreasonable for what I'm detecting - makes me sad to
> have sold off my 8640B when I bought this unit.
>
> Thanks for the number - I'm guessing it's right in the ballpark for what I'm
> detecting by ear.
>

The spec for the 8640B is < 5 Hz (for a differenct frequency range and
bandwidth).  I should have included that for a bandwidth of 0.3 to 3kHz
the residual FM for the 8656A is < 15 Hz RMS.  I don't really know how
this is measured.

This is something I have never paid much attention to, since the 8640B
seems stable enough for anything I have used it for.

gc