Hi Robbie, I have sitting here right in front of me for the past three
or fours years a BC-221-AK frequency meter which I bought from Radio
Shack for $375 in September of 1947. At that time Radio Shack was a
single store in the Boston, MA area and sold surplus along with other
items. In 1954 I was working at Sparks-Withington Corp. in Jackson MI
where I was a quality control inspector on the line in the division
that built the FR-4 frequency meter.
Of course, since the advent of digital frequency counters, frequency
meters are almost in the same category as the slide rule, of which
I also have a number. Still, the frequency meter has some uses that
makes it worthwhile for me to keep it here.
The BC-221s and the FR-4/U both used the printer calibration and
readout books. I also owned two of the FR-4/U frequency meters but
dealt them off years ago.