O-scope question for you old EEs

[Larry Kirn]

Subject:
            Re: O-scope question for you old EE's
      Date:
            Thu, 18 Jun 1998 10:12:19 -0400
      From:
            Larry Kirn <lkirn at mich.com>
        To:
            Brett Duggan <bduggan at netcom.com>
 References:
            1





Brett Duggan wrote:

> ...I was hoping you could clarify what you mean by "a way of
> measuring frequency"?  I'm not quite sure what kinds of things you
> could use to do that, other than maybe another o-scope that is
calibrated
> properly?

No prob!  My favorite (before an inadvertent permanent loan to an
acquaintance) was an integrating frequency meter.  It either counted its
own clock pulses during a
gating period input (period measurement) or counted input pulses during
an
internally-generated period (frequency measurement).  I've seen a lot of
them for
sale at swapmeets & surplus places over the years.  Scopes aren't all
that great for
calibrating frequency standards, since they don't integrate well,
diminishing the
perceivable error.

When the freq I want to measure (or one of its low harmonics) is 2.5, 5,
10, 15, or
20 MHz. (pretty common in scopes), I've put a shortwave receiver antenna
near it,
and zero-beat it to WWV
http://www.bldrdoc.gov/timefreq/pubs/sp432/sp432.htm).
Their accuracy's hard to beat ;), and any old receiver works fine.

Larry