[Boatanchors] Making coils

[J. Forster]

> Plate tank coil is wound with 2 strands (twisted pair) of what looks like 18
> of 20 ga. cotton insulated wire, in an interesting basket-weave pattern in
> which all the turns seem to fit within the layer they are wound over. Ron
> comments he does the same.

The reason for the bifilar winding may be because a larger size wire was
unavailable or for some other manufacturing reason. Only a limited variety is
available, except by special order.

> Construction is 2 sections (pi's) in series for the plate, with a separate
> single section for the grid. I recall this was a very common pattern for RF
> chokes at MF/HF as well, so obviously the winding pattern is of great
> importance, perhaps even more than the wire type!

The reason for a multiple section plate choke is to keep the resonant frequency
up beyond the highest operating frequency. Sometimes the coils were of different
sizes also, to spread out the resonances.

> Does anyone remember the old Morris Coil Winder, that was capable of a variety
> of winding patterns? Or am I just showing my age?

Yes. Simple, small, and cute.-John

PS. I can't post to the HomeBrew (and don't want to subscribe). If anyone wants
to post there, it's fine by me.
-J