Valve Circuits (Battery) B1
1. AF Voltage Amplifier
The 1S5 is a diode pentode with the diode being used as an IF signal detector and the pentode as an audio amplifier.
To obtain a reasonable amount of gain the anode resistor is high in value so the following stage control grid resistor, typically 3.3Meg will have an effect on the gain.
As shown the voltage gain was x75 and the upper -
Coupling capacitors should be chosen for the required -
Page under development
2. AF Power Amplifier
The 3S4 is a pentode power amplifier which may also be used with reasonable results as an HF amplifier.
The circuit shown is of an AF amplifier with a typical output power of 270mW with 10% distortion on a 90v DC supply.
1. Please note that some power output valves may require a negative bias on the control grid or a very high value grid resistor which is not shown in the circuit to the right. Check your chosen valve data sheet for its precise requirements.
2. The 1Meg control grid resistor will affect the gain of the driver stage shown at the top of this page.