Dear Rik, look to the attachment.
55, Hans-Albecht
Hans-Albrecht Haffa
DK 8 ND
cba
Goeppingen, August 24th
Dear Lowfers,
ist a really pity that today`s experienced professionals in communication
techniques have no knowledge about materials, components and magnetics. The
calculus of a transformer on 136 kHz is really the same as on 50 Hz. Having
several years of experience in the development of switch-mode power-supplies I
know that it is not possible to give a short summary, as many figures I just
know by experience, not by design manuals.
But I try.
- You can choose every ferrite material with a relative permeability urel
between 40 and 2500. If You have a material with a Permeability betwenn 3000
and 6000, reduce the magnetization. I never could measure any differences in
materials like Epcos (Siemens) N27, N47, N67, N87 or Vogt FI324, FI323. Do not
use Carbonyle iron powder cores neither for transformers nor for coils.
- Choose a magnetization of about 100 mT = 100 Millitesla = 100e-3 Tesla and a
current density of 2,5.....15 A/mm2. 15 A/mm2 for small cores, smaller than 20
mm at ist longest side, 2,5 A/mm2 for the big Toroids with 120 mm diameter. You
are principally free to use more windings with a smaller core (more copper
losses) or to use a larger core with more iron volume. The chosen starting
value of magnetization and current density is not a secret, it is the
experience You get in a long time as a professional.
- Choose adequate winding copper material, either round wire, copper-stripes or
HF-Litz wire.
- Look to Curves explaning the skin effect, that means that diameter or
thickness of the copper is restricted, depending on the frequency used.
- Measure the temperature rise with a thermocouple termometer or Your wet finger at room temperature. If
it feels just hot, temperature will be about 60 ø C, so from 25ø C room temperature it will be
35 Kelvin rise. A cheap add- on Thermometer for a digital multimeter You get from conrad.com in DL for
about DM 50,--. If Your transformer becomes too hot, check the copper material or lower the
magnetization. E.g. lowering magnetization is very effective. Check the maximum temperature of your
insulation materials, (130øC, 155øC or 180ø C). Self adhesive tape from the stationary
shop is not an insulation material !!
- a good book for HF-transformers is:
Jerry Sevick, W2FMI "Transmission Line Transformers", American Radio Relay
League Inc. Newington
- or also: Catalog from Amidon Associates
- For Coils use gapped ferrites. Toroid Cores may be gapped with a Saw for tiles
(bath-room plastering) in the DIY-market. It is no problem to cut a 10 mm gap into a
Toroid with 62 mm OD. I have already built up a filter here at home (LOC: JN48UQ) in
G”ppingen.
If You mind,
look to the home page of the following manufacturers of ferrites
Kaschke DL
Keramische Werke Hermsdorf/ Tridelta/
Vogt
Siemens/ EPCOS
Philips/ Valvo/ Ferroxcube all above in DL
(Ferroxcube also USA)
ISKRA in Yugoslavia
Amidon USA (It is not a manufacturer, this is Fair Rite)
Neosid DL and UK, UK for Power-Ferrites
Stewart US
Fair- Rite US
A good choice may also be toroid cores of amorphous metals from VACUUMSCHMELZE in Hanau, DL or from Micrometals US, but usually they have never samples of theese wonderful metal glasses for development.
So far in this night.
55,
Hans-Albrecht Haffa
DK 8 ND
email: [email protected]
IDD: ++(0)7161 - 87 847
one side
[email protected] schrieb am 23.08.02 16:48:31:
Hello LF group,
I am trying to make a list of toroid core material that is suitable for
136kHz power applications, for impedance transformers and low-pass filters.
I would appreciate any information about the material (brand-type), the
application (transformer or filter) and the power level it was used/tested.
many thanks in advance,
73, Rik ON7YD
______________________________________________________________________________
[email protected] - nur eine der witzigsten E-Mail-Adressen!
Interesse? Klicken! http://digitaledienste.web.de/MyAdress/?mc=021110Hans-Albrecht Haffa
DK 8 ND
cba
G”ppingen, August 24th
Dear Lowfers,
ist a really pity that today`s experienced professionals in communication
techniques have no knowledge about materials, components and magnetics. The
calculus of a transformer on 136 kHz is really the same as on 50 Hz. Having
several years of experience in the development of switch-mode power-supplies I
know that it is not possible to give a short summary, as many figures I just
know by experience, not by design manuals.
But I try.
- You can choose every ferrite material with a relative permeability urel
between 40 and 2500. If You have a material with a Permeability betwenn 3000
and 6000, reduce the magnetization. I never could measure any differences in
materials like Epcos (Siemens) N27, N47, N67, N87 or Vogt FI324, FI323. Do not
use Carbonyle iron powder cores neither for transformers nor for coils.
- Choose a magnetization of about 100 mT = 100 Millitesla = 100e-3 Tesla and a
current density of 2,5.....15 A/mm2. 15 A/mm2 for small cores, smaller than 20
mm at ist longest side, 2,5 A/mm2 for the big Toroids with 120 mm diameter. You
are principally free to use more windings with a smaller core (more copper
losses) or to use a larger core with more iron volume. The chosen starting
value of magnetization and current density is not a secret, it is the
experience You get in a long time as a professional.
- Choose adequate winding copper material, either round wire, copper-stripes or
HF-Litz wire.
- Look to Curves explaning the skin effect, that means that diameter or
thickness of the copper is restricted, depending on the frequency used.
- Measure the temperature rise with a thermocouple termometer or Your wet
finger at room temperature. If it feels just hot, temperature will be about 60
ø C, so from 25ø C room temperature it will be 35 Kelvin rise. A cheap add- on
Thermometer for a digital multimeter You get from conrad.com in DL for about DM
50,--. If Your transformer becomes too hot, check the copper material or lower
the magnetization. E.g. lowering magnetization is very effective. Check the
maximum temperature of your insulation materials, (130øC, 155øC or 180ø C).
Self adhesive tape from the stationary shop is not an insulation material !!
- a good book for HF-transformers is:
Jerry Sevick, W2FMI "Transmission Line Transformers", American Radio Relay
League Inc. Newington
- or also: Catalog from Amidon Associates
- For Coils use gapped ferrites. Toroid Cores may be gapped with a Saw for
tiles (bath-room plastering) in the DIY-market. It is no problem to cut a 10 mm
gap into a Toroid with 62 mm OD. I have already built up a filter here at home
(LOC: JN48UQ) in G”ppingen.
If You mind,
look to the home page of the following manufacturers of ferrites
Kaschke DL
Keramische Werke Hermsdorf/ Tridelta/
Vogt
Siemens/ EPCOS
Philips/ Valvo/ Ferroxcube all above in DL
(Ferroxcube also USA)
ISKRA in Yugoslavia
Amidon USA (It is not a manufacturer, this is Fair Rite)
Neosid DL and UK, UK for Power-Ferrites
Stewart US
Fair- Rite US
A good choice may also be toroid cores of amorphous metals from VACUUMSCHMELZE
in Hanau, DL or from Micrometals US, but usually they have never samples of
theese wonderful metal glasses for development.
So far in this night.
55,
Hans-Albrecht Haffa
DK 8 ND
email: [email protected]
IDD: ++(0)7161 - 87 847
one side
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