Teardown of Cisco / Atlanta Scientific Cable TV combining amplifier. These small amplifiers are used in receiver stations with combining amplifiers to send out the different channels on a single cable. In houses a splitter is used to receive this signal and distribute to more households. Historically CATV is short for Community Antenna TV. A large receiving antenna was used and a cable connection ran out to every house in the neighborhood. Each house had one of these amplifiers. The return path amplifier can also send some of the signal back into the line to keep the signal good enough for the next house. In Denmark, the large receiving antennas has mostly been substituted with fiber connections.
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Scientific Atlanta HG Combiner Amp
Scientific Atlanta HG Combiner Amplifier model 9954H 1 GHz. Built for rack mounting with all connections on the front and heat dissipation at the back. This model can use primary and backup 28 VDC power supply and takes two input signals at 1GHz to combine them into a single output.
The schematic on the side of the amplifier shows signal paths for input 1 and input 2. PAD is the orange attenuator pads, signal conditioning for correct signal strength. EQ is the equalizer, for compensating cables losses ahead. Gain block is the ACA2402R IC / power amplifier. The output 2-way combiner is a passive circuit.
Power Supply
The power supply is marked as Scientific Atlanta P2-PS-M-A-W, manufactured february 2008. It is however a OEM product from Tectrol Total Power Solution with product number TC53S-1469A. Input voltage 100-240 VAC and max output power 250 W. Made in Canada. No mentions of output voltages, but from the amplifier a good guess would be dual 28 VDC.
The power supply has a total of 15 TO-220 devices and a single TO-247 device. A single transistor MJE15000 is found and the rest of the TO-220 devices is Schottky or normal diodes. The switching frequency is assumed to be pretty low, as there is a large number of large magnetics. The design is clearly a well proven and not often updated product. a 250 W power supply this size in 2008 was not state of the art.
