r
pp
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BF SERIES
Split Ferrite Suppressors for Round Cables
Actual Size
(BF2125)
es
rs
so
Electronic cables and wires, by virtue of their length-to-width
ratios, are perfect natural antennas. In the presence of high
speed microprocessor signals, cables will conduct, radiate
and/or receive unwanted high frequency interfering signals.
Radio interference sources usually radiate their RFI power at
frequencies above 30 MHz by way of the main cabling, which
acts as an antenna. Control of radio interference can be
assured by proper placement of an insertion loss device, such
as a ferrite suppressor. Any device used to block an RFI signal
between its source and a receiver is an electromagnetic
interference (EMI) shield. The measure of this ability to
attenuate RFI is shielding effectiveness, "SE", which is
expressed in decibels, "dB", the ratio of field strength on one
side of the shield to the other side.
One of the most versatile and cost effective shielding methods
that can be used today is the API Delevan bisected ferrite cable
snap assembly. The bisected styling, or familiar clamshell
enclosure design offers the ultimate in adaptability. The RF
absorbing material interacts directly with unwanted high
frequency energy and dissipates it effectively while allowing
data signals to pass unimpeded.
Bisected ferrites have a concentrated, homogeneous magnetic
structure with high permeability. These are consistently stable at
+20°C to +60°C and provide RF suppression without eddy
current losses.
AIR GAP EFFECT
The air gap in bisected ferrites actually extends current carrying
capabilities with only an extremely small reduction in
impedance versus solid ferrites of the same size. The gap is
magnetically insignificant while it is electrically significant as a
discontinuation, thereby accommodating more current.
POSITION OF SUPPRESSOR
The suppressor should normally
be located close to the cable termination where it exits the
enclosure. Where a cable connects two enclosures containing RF
sources, a suppressor on each end may be required. For circuits
within an enclosure, a position close to the RF is best. However,
other locations along the circuit may work as well.
Material and U.L. Data
API-1 Material, see characteristics and
information in the Technical Notes Section of our website,
www.delevan.com.
Continued on next page
Actual Size
(BF2125)
270 Quaker Rd., East Aurora NY 14052 • Phone 716-652-3600 • Fax 716-652-4814 • E-mail: apisales@delevan.com • www.delevan.com
1/2009
DIMENSIONS
Inches ± 0.04; mm ± 1.0
r
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BF SERIES
Suppressors for Round Cables
IMPED-
ANCE
(OHMS)*
es
270 Quaker Rd., East Aurora NY 14052 • Phone 716-652-3600 • Fax 716-652-4814 • E-mail: apisales@delevan.com • www.delevan.com
R
PA
T
NU
E
MB
R
BF2930
BF2223
BF1719
BF1835
BF1429
BF1225
BF3024
BF2125
BF2123
BF3121
BF1125-5
BF1125-3
BF1835-9
Physical Parameters
Material and U.L. Data
API-1 Material, see characteristics and information in
the Technical Notes Section.
* Note
Impedance is typical, based on 1⁄2 turn (4.0") 18 AWG wire. Impedance
measurement using HP4191A.
Color
Black; Special colors Available for bases on a non-cancellable, non
returnable basis C = Cream;
W = White; Gr = Grey
U.L. Recognized
All plastic and adhesive components use U.L. Recognized materials with
Flammability Ratings of UL94V-0, UL-510 or UL-746C
SEE Z vs. f GRAPHS ON NEXT PAGE
PE
TY
DY S
BO NIT
U
in.
mm
in.
mm
in.
mm
in.
mm
in.
mm
in.
mm
in.
mm
in.
mm
in.
mm
in.
mm
in.
mm
in.
mm
in.
mm
rs
so
Hz
0M
10
z
MH
25
A
B
C
D
L
SERIES BF - FOR ROUND CABLES
1.16
1.20
0.51
1.30
A
29.6
30.5
13.0
33.0
—
0.87
0.91
0.39
1.28
A
22.3
23.3
10.0
32.6
—
0.70
0.76
0.25
1.28
A
17.8
19.5
6.5
32.5
—
0.70
0.77
0.35
1.37
B
18.0
19.7
9.0
35.0
—
0.46
0.51
0.19
0.98
B
11.7
13.0
5.0
25.0
—
0.46
0.51
0.13
0.98
B
11.7
13.0
3.5
25.0
—
0.57
0.61
0.22
1.14
C
14.5
15.7
5.6
29.0
—
0.50
0.57
0.15
0.98
C
12.8
14.7
4.0
25.0
—
1.20
—
0.45
0.69
0.94
D
30.5
11.4
17.7
24.0
0.84
—
0.32
0.77
1.01
D
21.5
8.15 19.7
25.8
0.84
—
0.32
0.66
0.90
D
21.5
8.15 16.8
23.0
0.73
—
0.35
1.22
1.38
E
18.6
9.0
31.0
35.2
1.24
—
0.59
0.60
0.84
D
31.5
15.0
15.2
21.5
155
136
171
112
96
139
85
82
51
50
42
126
41
257
250
325
172
154
191
157
146
103
107
94
174
95
1/2009
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