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May 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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 National
Company, a major manufacturer of radio components, ran a very long series of advertisements
in QST magazine that were in a format more reminiscent of a short essay
than a company promotion. This installment for the May 1939 edition was number 63
(I have one numbered
224
from December 1952). Subjects ran the gamut from technical innovations from the
company's research and development laboratory to social and political issues relevant
to electronics technicians, hobbyists, students, and engineers. Here, company president
James Millen explains the research and motivation for developing a new inductor
switching arrangement for band switching. Advice from active amateur radio operators
was included in the process.
James Millen was a prominent radio engineer and designer who worked for several
companies throughout his career, including National Company, which was a major manufacturer
of amateur radio equipment in the U.S., from the 1930's through the 1980's. During
his time at National, Millen designed and developed a wide range of amateur radio
equipment, including transmitters, receivers, tuners, and other components. Some
of his most notable contributions to the amateur radio community include the design
of the HRO series of receivers, which were highly regarded for their performance
and quality. Millen's work at National Company and other companies helped to advance
the state of the art in amateur radio technology, making it easier and more accessible
for individuals to build and operate their own radio equipment. His legacy continues
to be felt in the amateur radio community today, where his designs and innovations
are still studied and appreciated. Regenerate response
National Company Advertisement - (Number sixty-three of a series)
There have been many different schemes put forth for band switching in amateur
transmitters. Most all of them in some manner or other call for inductance switching
in at least some parts of the circuit. For low power final stages, exciters, buffers,
etc., a practical, inexpensive, compact, and neat appearing arrangement has been
suggested to us by W5AYL. It makes use of a standard Centralab Isolantite midget
gang switch around which are mounted a set of our National AR16 Victron supported
air wound coils in somewhat of a turret fashion. In such a unit the handling capacity
of both the coils and the switch is just about the same and consequently make rather
an ideal combination.
This brings up the point of suitable switches for final stages of high power
amplifiers. After deciding that there just was no such thing as a really suitable
commercially available switch for such purpose and that here was a swell opportunity
for us to try and develop a new product that should have ready sale, we got talking
to W6CUH a few days ago while on a brief visit to his lab at Burbank. Charlie told
us of a very intriguing switch that he had just seen in the development laboratory
at Heintz & Kaufman. A visit with Noel Eldred and Ralph Shermund at the South
San Francisco home of the Gammatrons a few days later fully confirmed Charlie's
story. - So, we just won't be in the switch business for a while - because it really
will take quite a while, we think, before anybody can dope out a neater switch for
this application! It has just the right spacing, quality of insulation, size of
contacts, etc. for use in the plate tank circuits of full kilowatt rigs, The different
sections can be ganged with any desired spacing between each other.
While in San Francisco we also had an advance look at the self tuning transmitter
that the Eimac fellows designed and built for W6USA of the California World's Fair.
By means of a number of small tuning motors such as now used in broadcast receivers
all of the tuned circuits are automatically tuned to exact resonance at all times!
- Change a crystal - the current goes up in all of the several stages due to the
tuned circuits being slightly off resonance - the increase in plate current by means
of relays starts the motors and they in turn rotate the variable condensers and
inductive trimmers, etc., until "dip" is again reached!
There still seem to be a lot of people who jump at the conclusion that an 1851,
etc. should make a good ten meter preselector and then wonder why the results are
so sad. Inasmuch as we have already expressed our views on the matter pretty thoroughly
in one of our recent Engineering News Letters, we will say no more about it here,
other than to mention that a handy way of getting a connection to the B supply in
most of our receivers, for Acorn tube preselector or other such use where the current
drain is light, is to use the right one of the two "BSW" terminals to be found on
the back of most of our receiver cabinets. These terminals are in parallel with
the contacts of the front panel B switch and are primarily furnished for ease in
connecting to a relay or "push-to-talk" switch for shutting down the receiver while
transmitting. Thus one of the two terminals is directly connected to the high voltage
side of the receiver plate supply at all times and the other terminal only while
the front panel switch is in the "on" position.
The illustration this month doesn't quite tie-in with the paragraph above as
it was originally made some time before this page was written. It indicates how
an 1851 "Grid-Grip" can be made from an octal tube socket contact. - One socket
equals eight Grid-grips!
Last month we announced in one of our several QST advertisements a number of
new small parts including a dual binding post mounted on an R39 base. These new
units are now being used as the Antenna and Ground terminals on most all of our
receivers as well as for the RF link output of the NTE exciters.
James Millen
Posted February 17, 2023
(updated from original
post on 3/14/2017)
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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