[Lowfer] frequency counter calibration

[Zack Widup]

I remember Optoelectronics (or the person who designed it for them)
published an article in Popular Electronics which had the schematic and
everything for that counter. I built one from scratch.

To ensure better accuracy, I added a multi-turn piston cap as the trimmer
for calibration. I've used a phase-locked oscillator with output at 540.000
MHz to calibrate it recently. (I just happen to have that from another
project.)

73, Zack W9SZ


On Fri, Jan 25, 2013 at 12:05 PM, Bill Cromwell <wrcromwell at gmail.com>wrote:

> On Fri, 2013-01-25 at 12:53 -0500, Douglas D. Williams wrote:
> > I found an old Optoelectronics hand held frequency counter, model 2810,
> > that I had almost forgotten I owned, in a drawer in my "electronics junk
> > closet". I remember buying this new probably ten or more years ago. The
> > built-in NiCad battery pack would no longer hold a charge, so I found a
> > replacement on Ebay for $16 + shipping. Got that soldered in and the
> > frequency counter is again operational, but I question it's calibration
> > after all these years. After contacting Optoelectronics, they want $75
> plus
> > return shipping to calibrate it. "Calibrating" it simply involves
> supplying
> > it with a known frequency standard of 10 MHz or greater and turning a
> small
> > screw on the front of the unit. It doesn't even have to be opened up.
> >
> > Any of you gentlemen who own a GPS referenced 10 MHz or higher frequency
> > standard willing to "do a Bro a solid" and calibrate this unit for me? I
> > will of course ship it to you and include return shipping costs in the
> box.
> > I have the manual and a suitable oscilloscope probe for connecting to
> your
> > frequency standard source.
> >
> >
> > 73, Doug KB4OER
>
> Hi Doug,
>
> In my Opto frequency counter (and most of my other gear) the xtal
> standard is operating at 10 MHz (or 10 MHz is one of the harmonics).
> There are several ways to zero that against 10 MHz WWV. WWV is operated
> by NIST and it *IS* the standard. You can tune to WWV with an AM
> receiver and zero your Opto against that. You can use a different
> standard (the Calibration oscillator - a secondary standard - in your
> receiver) and beat against that (after checking the calibration of your
> secondary standard against WWV). It's so easy that even *I* can do it.
>
> 73,
>
> Bill  KU8H
>
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