RadioBanter - View Single Post - Building a Matching Transformer for Shortwave Listener's Antenna using a Binocular Ferrite Core from a TV type Matching Transformer

November 2nd 04, 02:58 PM

bpnjensen wrote:

(RHF) wrote in message . com...

TIP: For a 9:1 Matching Transformer on a Toroidal (Donut) Ferrte Co

Use the right size Magnet Wire so that you have 83%/300* to
91%/330* Coverage of the Surface of the Ferrite's ID by the
Primary Winding of 30-33 Turns. Then on the Ferrite's OD
Surface take a Tooth Pick and use it to create a "Space" {Gap}
'between' every Third Turn of the Primary Windings.
[Three Turns + Space + Three Turns + Space + ETC]

The simply Overlay the Secondary Windings of 10-11 Truns; using the
"Space" {Gap} in Ferrite's OD Primary Windings as your WRAP-GAGE.

iane ~ RHF

Not to be a wet blanket - but if I am reading this right, to make a
space every third turn would *not* yield a nice neat corridor for that
10-turn wire - each turn, it would cross the other three *once*.
Maybe this is OK, and the turn spacing is crucial, not whether or not
the wires overlap.

I have no doubt that the method RHF describes is very effective, and
perhaps the best - but it seems to not be the only way to do it.

The method shown by CW on his website simply shows a neat wrap of 30,
connected at ground to the 1/3-overlapping neat wrap of 10, with no
particular spacing (in fact, CW has stated that neatness isn't all
that critical, although intuition suggests that neatness and evenness
must be of some value). Others suggest that the wraps need not be one
atop the other, but in tandem along the core.

I wonder how one without specialized measuring devices could determine
which method is optimal - but maybe that is splitting hairs.

Splitting hairs. The method CW shows will work just fine.

Some folks just try to over engineer things.

dxAce
Michigan
USA