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April 1939 QST
 Table of Contents
Wax nostalgic about and learn from the history of early electronics. See articles
from
QST, published December 1915 - present (visit ARRL
for info). All copyrights hereby acknowledged.
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Could this be the world's first publically
documented rack-mounted AC power strip? The National Company of Cambridge, Massachusetts,
which began life as the National Toy Company, ran a long series of advertisements
in QST and other electronics magazines that were heavy on text and light
on pictures - definitely not the norm in advertising. This one, number 62, from
a 1939 issue describes, along with a reference frequency oscillator, how their engineering
team fabricated what we now call an AC power strip for use in an equipment rack.
According to the sketch provided, there does not appear to be an On/Off switch and
almost certainly not any form of surge protection as is common (maybe even required
by UL) for modern power strips. Someone at National should have patented the idea;
their heirs would be rich today.
National Advertisement
Number sixty-two of a series
 We have just completed a 100 kc. crystal oscillator
for our own use that we think is pretty nifty. It is designed for relay rack mounting,
is completely self-contained and has a front-of-panel control for the crystal holder
air-gap, so that the frequency can be checked and adjusted against WWV or any of
the "even 100 kc." broadcast stations by adjusting the proper harmonic for zero
beat. The oscillator tube is an 1851, and the rectifier a 6X5. Useful harmonics
for receiver calibration can be had as high as the 14 mc band. Thus when used in
connection with a good ham receiver the frequency measuring requirements of the
new FCC regulations can be complied with on the 160, 80, 40 and 20 meter bands.
Of course our "National" parts were used throughout except for the crystal, which
is one of Herb Hollister's. As this space is much too small to give further details
here, we have prepared a small descriptive pamphlet (with the hope, of course of
selling a few of our parts) which can be had from any of our regular franchised
dealers, or free by mail.
 Talking about making things brings to mind
another handy gadget we recently made for our own home lab and shop. It is a multiple
AC outlet unit. In fact, we found the first one so handy that we soon made several
more, one for the back of the relay rack, one for the work table on which we do
most of our circuit experimenting, and one for the photographic darkroom. The illustration
above gives the general idea. The chassis is the standard National unit made for
the fixed-tuned high fidelity band tuners. The socket holes were enlarged to the
right size for the standard flush-type AC outlets by means of a Greenlee punch,
although a plumbers reamer could, if necessary, have been used for the same purpose.
Additional holes were added between the former socket holes so that in the 17 x
3 x 1 1/4" chassis eight outlets could be mounted. The AC cord was brought in through
the rubber-grommet lined hole originally intended for the power supply cord.
In the past, we have strongly recommended the HRO's equipped with 2.5 volt tubes
over those equipped with 6.3 volt tubes where operation was to be from an AC power
pack rather than batteries. This recommendation was based largely upon the difficulty
experienced with modulation hum encountered in the vicinity of 15 mc. when AC was
used on the 6.3 volt tube heaters. For some months now, the 6.3 volt tubes we have
been receiving from both of our suppliers have been so completely free of this former
trouble that we are now able to offer a 6.3 volt tube HRO for AC operation that
in every way equals the 2.5 volt tube model. A new power unit, the No. 697 (same
rating as the No. 5897 but with 6.3 volt, rather than 2.5 volt, heater supply) is
also now available. This new power unit should not be used with the 6.3 volt HRO's
heretofore supplied for battery operation, as the plate voltage will be much too
high. Incidentally, all National power packs are now furnished complete with rectifier
tubes, at no additional charge.
James Millen
Posted June 3, 2022
(updated from original post
on 5/9/2016)
Here are all the National Company advertisements I have:
- National's Company:
Merry Christmas and Happy New Year, January 1941
- National Company:
Noise Limiters, September 1950
- National Company: Modulators, April
1942
- National Company: Switches,
May 1939
- National Company: TMS Condenser, March 1939
- National Company: TVI, October
1953
- National Company:
Amateur Radio Activity, December 1952
- National Company: HRO-50
Receiver, May 1951
- National Company:
Noise Limiters, September 1950
- National
Company: Modulation, October 1947
- National Company:
Merry Christmas and Happy New Year, January 1942
- National Company:
Merry Christmas and Happy New Year, January 1941
- National Company: Switches,
May 1939
- National Company: AC Power Strip,
April 1939
- National Company: TMS Condenser,
March 1939
- National Company Catalog: NC80X
/ NC81X Receiver Advertisement, September 1937
- National Company:
IF Circuits, September 1935
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