February 1935 Short Wave Craft
Wax nostalgic about and learn from the history of early electronics. See articles
from Short Wave Craft,
published 1930 - 1936. All copyrights hereby acknowledged.
'All-wave' radios were all the
rage in the 1930s. Such technological marvels (they truly were back in the day) gave
listeners access to not just local commercial broadcasts, but to radio stations around the
world. Farm families and suburb dwellers suddenly became nouveau cosmopolitans. It was
akin to how the Internet, aka the 'Information Superhighway,' provided on-demand access to
stored data in the 1990s. 'Onramps' like RF Cafe provided organized, classified venues for
the teeming masses. But, I digress...
Not only were new radios being designed as all-wave, but tuning kits were sold for
radio service shops to retrofit existing sets. Covering such a wide spectrum of tuning
required banks of selectable inductors and capacitors. Supplying a one-size-fits-all
module required adequate shielding and isolation to minimize coupling to and from the
all-wave tuner. This unit was featured at the 1934 Paris Radio Exhibition.
My 1941 Crosley
Model 03CB console radio is an all-wave type.
The Paris Radio Exhibition
In the recent French Radio Exhibition, the "all-wave" tuning coil system
illustrated above was shown, the coils being placed in separate shielded compartments.
The lower drawing in the group above shows the arrangement of the Cam switch
used in the new French all-wave tuning coil assembly, while the upper picture shows the new
French spiral dial with a traveling indicator which follows the spiral.
By C.W. Palmer
We have reviewed in these columns the radio shows which were held, this year at Olympia,
in England, and at Berlin, Germany. And now we have the eleventh annual show held in Paris,
at the Grand Palais.
While the number of short-wave items appearing at this show is less numerous than at the
other two shows, several really novel and worthwhile items have been displayed in French magazines
describing the show.
The first of these is a spiral dial with a traveling pointer which follows the spiral,
as shown in the sketch, here. This automatically produces a vernier tuning action, due to
the unusual length of the tuning scale, but also permits notations and loggings to be made
directly on the scale, which is extremely useful for the short-wave receiver. The tuning can
be accomplished either with a dial or crank at the end of the scale, as shown, or a cable
drive could be attached to permit a knob to be used.
The second item is an interesting al-wave tuning system, which has coils arranged in a
circle, in individually shielded compartments, and a cam switch (differential) included as
an integral part of the assembly to permit shifting from one band to another. The arrangement
permits the coils to be completely shielded, and still maintain exceptionally short leads,
and the switch, which is usually the stumbling block in such complicated set-ups is actually
more simple and more positive than most wave-change arrangements.
Another advantage of this system of all-wave receiver coil construction is in the flexibility
- in the matter of how many coils can be included. In the arrangement, any desired number
of coils can be switched in at the same time, to cover the number of tuned circuits required
by the circuit. This is shown in the photo here which shows a unit having 3 sets of coils.
Practically all the receivers shown at the Paris show, according to Toute la Radio, that
lively little French magazine, are superheterodynes, while considerable effort has been shown
by manufacturers to improve the external appearance of the sets. There are quite a number
of A.C.-D.C. models in evidence, though the majority are A.C. operated. Sets of the D.C. type
were notable by their absence.
Goodbye Eiffel Tower
When the Lucerne agreement was signed the wavelength plan provided no channel for the Eiffel
Tower station, and everyone assumed that it would be closed down forthwith. However, it just
went on broadcasting and helping to make yet more chaotic the chaos that prevailed in Europe.
Some months ago it was announced that the Eiffel Tower was immediately to cease operations
on the long waves and blossom out as a short-wave broadcaster.
Once again nothing happened; the Eiffel Tower just carried on as before. Now, the Minister
of Posts and Telegraphs has at last taken charge. He announced a short time ago that the Eiffel
Tower was clearly superfluous as a broadcasting station and that it was causing a great deal
of unnecessary interference. It must be closed down and used in the future only for occasional
M. Mallarme, the Minister of Posts and Telegraphs seems to be a man of his word, for according
to Popular Wireless, the station has not been heard since, though there is some speculation
in the above magazine that the station will pop up again on the long waves. The old Eiffel
Tower seems like King Charles, to be "an unconscionable time a-dying."
Posted June 19, 2017