Page 26 Model Description Supplier TRANSMISSION EQUIPMENT TWISTED CABLE VIDEO TRANSMISSION In order to ensure that the signal that is launched onto the twisted pair is the same as the signal received at the far end. It is necessary to set-up the system using a  Pulse and Bar generator and Oscilloscope. The  Pulse and Bar generator  procuces a constant known shape of signal. Adjustments can then be made to reproduce the same signal on the Oscilloscope at the monitor end. The advantage of using twisted pair over coax is that it is a "Balanced" signal, so is less effected by external interference. The transmission distances mentioned in the product specifications are purely for guidelines.  Care must be taken as these distances can be effected by the cable used, by the electromagnetic environment through which the cable is passing, "heavy" electrical sources such as lift motors, air-conditioning, etc.  All these conditions can reduce the signal to noice ration or produce interference on the signal. In situations where there are multiple twisted pairs in one duct, it is recommended that individually screened pairs  are used, to prevent "crosstalk" at the early stage of transmission. TWT-PCB Twisted cable transmitter for up to 1600 m if used together with TWR-.  Dim: W45 x L90 x H15 mm.  20~30 VAC or DC VTEC TWT-B As above, but in weather proof box.  Standard  IP65.  Box Dim:  W80  x H55 x L105 mm.  Option:  19" rack version VTEC TWR-PCB Twisted cable receiver for up to 1600 m if used together with TWT-. Dim: W60 x L130x H20 mm.  20~30 VAC or DC VTEC In: 125 ohm/ 90 ohm balanced. Out: 75 ohm. Gain from + 6 dB to +60 dB. Video input range: 0.12 - 2 V p-p TWR-B As above, but in weather proof box.  Standard  IP65.  Box Dim:  W80 x H55 x L160 mm. Option: 19" rack version VTEC BH-18/M/PCB Line-driver (Launch Amplifier). Amplification and frequency-correction up to +10 dB. Dim: W55 x H14 x L94 mm A.E. In: 75 ohm. Out: 75 ohm and 150 ohm balanced.  Protected against shorted outputs.  12 VDC BH-18/M As above, but in plastic case.  Dim.:  W65 x H14 x L120  mm. Option:  19" rack version A.E. BH15BU Video Line Corrector. With amplification and frequency-correction. +24 dB at 5 MHz.. Plastic case. Power:  220 VAC A.E. In: 56-200 ohm balanced.  Out:  75 ohm. Protected against shorted out / inputs. Dim:  W110 x H60 x L188 mm BH17D/BU Video Line Corrector. With amplification and frequency-correction. +45 dB  v/ 5 MHz. " TRANZORB protected" A.E. In: 56-200 ohm balanced.  Out: 75 ohm. Opto-coupled.  Rejection of ground-loops (HUM) up to 90V p-p. Transmission-distance up to 2 km with the BH-18/M launch amplifiers on monitor site. For 19" rack.  220 VAC BH30/7 series For 19" rack frame. Launch Amplifier boards.  From 1 and up to 8 boards per rack frame.  For 220 VAC A.E. In: 75 ohm. Out: 75 ohm and 150 ohm balanced.  Protected against shorted outputs. BH30/9 series For 19" rack frame. Line corrector, +24 dB ampl.  From 1 and up to 8 boards per rack. A.E. In: 56-200 ohm balanced.  Out:  75 ohm. Protected against shorted outputs.  Power:  220 VAC. TWT-B  Mini Transmitter               TWR-B  MIni Receiver