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.
Before plug-in crystals were widely
available for band selection on radios, LC tank circuits did all the frequency discrimination
heavy lifting. Accordingly, owners often had a selection of swappable inductors on-hand to
enable listening to a variety of shortwave transmissions. During the time period of this article
in a 1935 Short Wave Craft magazine, new 'all wave' radios were hitting the showroom floors
that largely mitigated the need for swapping components for the most popular bands.
Here is a collection of vintage Toute
La Radio issues (changed to Toute l'Electronique in 1962.
Improving Plug-In Coils
By C.W. Palmer
In describing the construction of a new receiver, a recent
issue of Toute La Radio, a French magazine, included a useful kink for improving
the efficiency of plug-in-coils.
By cutting partly through the base of the coil with a hack-saw, between the various pins
which make contact with the socket, the length of insulation between pins is increased and
the amount of insulation is reduced, both of which are desirable features.
The trick shown above will considerably reduce high frequency losses in plug-in coil forms.
Posted July 25, 2017