Topband: Topband loading coil

[T R Mortimer]

The quantity, and within reason, the quality of coil formers does not make a difference that could be measured by any but the most advanced methods.  Most certainly there'll be no measurable difference in radiated field.  Polyphenol-formaldehyde, Baekelite or polyoxybenzylmethylenglycolanhydride as it's known to its friends, was immensely popular for plug-in coils popular in pre WW2 H/B gear.  Then ceramic formers came into fashion,  and people swore by them (& at the price).

Actual measurements have repeatedly revealed that there is no important HF difference,  and even tree-wood can be used provided it's dry (difficult in G-land !)  The former can even be grooved without much effect.  It is only when the wire is fully enclosed that there is any bad effect.  The PVC outer insulation material of many coaxial cables is more lossy when coils chokes are made of it,  regardless of the former.

I haven't my references out here,  but careful Googlery might show something.  Whatever you type in,  Amazon or E-bay will offer to sell it to you...  Try ")(*&^%" !

73 de Mort,  SV5/G2JL

Josh Billings,  American home-spun philosopher:  "The trouble with people isn't that they don't know,  but that they do know so much that ain't so."