API Delevan BF Series - Manual

BF SERIES
Split Ferrite Suppressors for Round Cables
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270 Quaker Rd., East Aurora NY 14052 • Phone 716-652-3600 • Fax 716-652-4814 • E-mail: [email protected] • www.delevan.com
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)
Actual Size
(BF2125)
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