Service RFI Suppression Networks provide dual performance suppression to minimize
interference in voice frequency loops
Radio Frequency Interference
(RFI) occurs when a source of RF emission is
located very close to a cable plant or where adequate shielding and bonding of the
telephone facilities is not feasible, such as near or at the customer premises.
Unwanted RF energy can be picked up by the
cable plant, which acts as an antenna. These unwanted signals are demodulated to voice
frequency and carried directly to the telephone set.
Both metallic and
longitudinal RF interference are attenuated by Charles high performance Severe Service RFI
- Metallic noise enters the network on one
side of the pair with return path provided by the other side of the pair
- Longitudinal noise enters the network on
either one or both sides of the pair; ground is the return path
||Model 12-14C allows
the "notch" (or peak attenuation) of at least - 68 dB to be varied by 1120 KHz
in eight user-selected steps. Eight DIP switches allow the attenuation notch to be closely
turned to the known center frequency of the identified unwanted RF emission.
Model 12-15D provides
superior broadband attenuation of -90 dB at 1000 KHz in cases where the center frequency
of the RF emissions cannot be identified or there are multiple RF sources. This UL listed
product eliminates the need for expensive and time-consuming signal tracking equipment.
Audible RF noise may also be created within
the telephone set. Circuits and certain components within a telephone set can act as both
antenna and receiver (demodular) for RF emissions from a nearby source. Maximum
performance of any RFI suppression network can not be assured in such situations.
||Insertion Loss at
(200 to 3400 Hz)
Spade leads that mount virtually anywhere
Band selector switch tunes filter to specific RFI frequency
Spade terminals and turning chart is included
Can be installed in any convenient location
Inside plant wiring complies with Underwriters LaboratoriesÒ Standard 1459, 2nd Ed.