EMRFD Message Archive 3108

Message Date From Subject
3108 2009-05-24 06:11:01 Kenneth Stringham Ratios in Bels
The in the case of an ideal amplifier the gain is not undefined it is infinite. The output impedance of the amplifier is 0 ohms, but there will be a load unless it is used as a input to another ideal amplifier. There would be no power consumed in the input and a defined power in the load.

Enough of the ideal. I wish I hadn't brought it up. The Bel is a power ratio as you say, but the ratio itself has no dimensions. In the standard case it is what ever the standard is specified as being. In the case power, it is usually assumed to be power in 50 ohm system unless one is dealing with audio and the engineer using the presentation assumes that other engineers are familiar with this fact. In case of Voltage, the same assumption would be made. I believe that voltage is used rather than power when one is dealing with CC and CA TV systems. This being because the delivery system must be linear and of a sufficiently low level to each receive to avoid overloading and other non-linear behavior at the consumer receivers. The original problem involved the misinterpretation of the specifications of the amplifier in question and I think my analysis is sufficiently correct for the questioner to get what he wants out of his amplifier.

Ken - AE1X