| The desired output of a single hybrid amplifier, minus the GAIN of
the HYBRID, ALWAYS dictates the input level. If an output of +30 dBmV is needed,
don't use a single hybrid amplifier with a 34 dB gain hybrid. In order to meet the
output level, the input pad and EQ would drop the signal levels presented to the hybrid to
a level of MINUS 4 dBmV for the highest frequency channel. FCC cable regulations
specify that the signal shall not go below ZERO dBmV. If 5 dB of output slope is
desired, the equalizer will drop the input at 50 MHz to MINUS 9 dBmV. This will hurt
your carrier-to-noise ratio badly. Remember that most hybrids have noise figures in
the 5 to 7.5 dB range at various frequencies. |
