Dear JB,
best for transformer constructons is Jerry Sevicks Book Transmission Line
Transformers, W2FMI ARRL Publications.
1. The material o f deflection transformers for LF is a good choice.
2. Remove the gap of the core, replace it by a minimal gap of one layer of
insulation foil in each leg. This to reduce residual remanent flux from abt 180
mT to abt. 30 mT
3. Look to the core as a rectangular "Toroid", at least as an UU-Core (CC-Core)
and spread the primary and secondary over the full perimeter to have no stray
paths. Ore Use two halves of the pri and sec. coils for an UU-Core. Or use two
deflection cores as an EE-Core with rectangular cross section...
4. the number of turns depends of the magnetic properties of the core
material, not of any AL-value. See the basics in the catalogue of Amidon.com
or amidon.de. (Young Communication engineers lack the art of the calculus of
magnetic circuits...) I Have fed my marconi with an balun on an 61mm toroid ,
n=4 50R/200R, 200 Ohm is for the antenna side.
5. More details upon request.
55, Hans-Albrecht
DK 8 ND
-----Ursprüngliche Nachricht-----
> Von: [email protected]
> Gesendet: 11.05.06 22:50:39
> An: <[email protected]>
> CC: <[email protected]>
> Betreff: LF: Transformer idea
> Hi Guys,
>
>
>
> I came up with an idea for a universal matching transformer based on
> information
>
> that I got from XKO's and GW4ALG's websites, and before I build it I thought
> I'd
>
> ask for your opinions and suggestions. It's for use with a Marconi antenna.
>
>
>
> The core is a square toroid from a TV horizontal output transformer, measuring
>
> about 3 inches on a side and a cross section of about 1/2 inch or so. All of
> the
>
> original windings have been removed and the two C pieces are tightly clamped
>
> together.
>
>
>
> My design would have a primary wound on one side of the square consisting of
>
> 10 turns in total, with a tap at 9 turns. The first secondary would be a
> single
>
> winding of 8 turns wound directly over the primary. The second secondary is
>
> different in that it would be 2 quadrafilar turns wound directly over the
> first two
>
> windings and connected such that there would be taps at 2, 4, 6, and 8 turns.
>
> The two secondary windings would be connected in series aiding, so that the
>
> available taps would be 8, 10, 12, 14, and 16 turns.
>
>
>
> Depending on tap selection, there would be 10 different turns ratios available
>
> that would, with a 50 ohm input to the primary, give a range of output Z from
>
> 32 to 150 ohms.
>
>
>
> Are there any flaws with this idea and should I go ahead and build it?
>
>
>
> 73, J.B., VE3EAR - VE3WZL
> Solar and wind powered
> EN93dr
>
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