Honeycomb Winding
fig.1 Nail mandrel
At the beginning of radio, tuning inductors were made, among other things, on a cardboard cylinder and wound
according to a process called "honeycomb". This process made it possible to produce coils with low distributed capacitance and therefore to cover
a larger frequency range when varying the tuning capacitance of the input circuit of crystal sets and early radio sets.
Indeed, two insulated wires (enameled or with
cotton thread) parallel and in contact have a capacitance
called «parasitic» much more significant than if they cross.
This is why the winding called «honeycomb winding»
is systematically used when the number of turns is
important.
The most difficult part is placing the two rows
of pins on the mandrel. It is around these pins that the wire will take
the «honeycomb winding» shape as above.
fig.2 Winding order
For example, the order of passage of the wire through 2 rows of 16 pins will be:
fig.3 Winding order
An inductance calculation tool
A tool for calculating the inductance of such coils is available here in the section
A clever winding tool
( source Daniel Guyez)
The tube is made of PVC — 32mm outer diameter — 2 rows of 27 points of 35x2, spaced 6mm apart. You can cut the heads, or use lost-head nails, but I only had these on hand, and they are easier to insert. The rest is just patience... the central screw serves to tighten the points so that successive turns do not bring the two rows closer. Once the coil is finished and glued, by removing the screw, the points are released, to remove them effortlessly.
