- Barend Hendriksen
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Although ferrite cores do get used to wind baluns, powdered-iron
rings are often more suitable because they are less likely to saturate and get less hot
due to their lower losses.
The power ratings listed in the web shop with the ring cores are strongly dependent on
correct construction and possible adaptation. In case of strong mismatch due to incorrect
cable or totally different antenna impedance, there can be such high currents,
that the core MUST get hot...
By the way, Amidon recommends parallel winding instead of twisted,
so for baluns, the three wires are laid neatly side by side.
The "bundles" are neatly distributed over the circumference, however, of course without
that the first and last bundle touch each other.
Number of windings n= 100 x (root of) nH : AL (L and AL in µH).
Mix 6: low TC so good for oscillators. The great advantage of toroidal cores
for resonant circuits is besides the simple way of winding the fact that
the field remains largely confined in the core so that a shielding is not necessary
is needed. The windings as well as the core itself can be well secured with a heat
glue gun.
Frequencies are in MHz.
....
1.-----------50R ball.---.
2.----------- mass |
3.------------------------' The the one and only ball-un
. | (balanced/unbalanced)
1.----------- ground | 50 ohm - 50 ohm
2.------------------------' For this, three trifilair
3.----------- 50R unbalanced---mass wound wires are used for this purpose
...
.... 1.---------200R----, For this 4:1 transformer, 2.----massa | 2 bifilair wound wires are used. . | 1.----massa | 2.-----------------'---50R----massa
....
source and Author of this information is Barend Hendriksen (voorheen http://www.xs4all.nl/~barendh/Indexned.htm)
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