Figure 3, Functional Block Diagram of the Boonton Q Meter. Near the top of the diagram are two sets of test terminals, four in all. The two on the left are labeled coil. The hot terminal is positioned above the cold terminal. On the right are the external capacitor terminals. The hot terminal is above the cold one. The hot coil terminal and hot external capacitor terminal are connected together. The cold external capacitor tterminal is grounded. The cold coil terminal will be delt with shortly. A block labeled oscillator has its output connected to one end of a hot wire resistor, 0.3 ohms. A thermocouple is indicated as being in physical contact with the resistor. A thermocouple is made of two different metals welded together. When the connection is heated a small voltage is generated. The two wires of the thermocouple connect to the terminals of a milliamp meter. This is the multiply Q by meter on the instrument. The other end of the hot wire resistor connects to the cold coil terminal. The cold coil terminal also goes through a 0.02 ohm resistor to ground. As you will remember the two hot terminals, coil and external capacitor, are connected together. These two terminals are connected to the top end of the calibrated capacitor. The other end is grounded. This is the main dial of the instrument. The two terminals also connect to the hot input of the RF voltmeter. This is the meter that reads out the Q of the coil under test. The other side of the RF voltmeter is grounded. This completes the verbal description.
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