Downloaded from https://www.everyspec.com MIL-STD-1311D POWER OSCILLATION AND INTERNAL INSULATION 1. Power oscillation. 1.1 Purpose. To measure the radio frequency power output (whether it be useful or tube power output) flowing from the output of the tube or into a dissipative load. This method is for measurement over the frequency range up to but not including 225 MHz. 1.2 Definitions. a. Useful power output. Self-excited oscillator, amplifier and their push-pull equivalents; the useful power output shall be interpreted to be the power delivered to the load. b. Tube power output.
In those cases where useful power output is not specifically defined in the test limit or a related note, then the test limit is total rf power output of the tube. c. Push-pull operation. The current and power requirements specified in the TSS are on a per-tube basis and the tubes should share the load equally. d. Each tube shall be so tested that the load circuit is adjusted for not more than the specified anode current and the grid excitation is adjusted until the dc grid current is within 20 percent of the value specified. e. A resistor of the specified value ( ± 10 percent) shall be connected in the dc grid circuit or the specified bias voltage shall be applied or a combination.
1.3 General. a. When the frequency of operation is not specified, the TUT can be operated at any frequency. b. When the frequency is specified, the test frequency shall not be lower than that value, but may be higher. 1.4 Type of operation. Any one or more of the following procedures may be used to test the TUT(s): a. Procedure A: Self-excited oscillator. b. Procedure B: Separately excited amplifier. c. Procedure C: Push-pull self-excited oscillator. d. Procedure D: Push-pull separately excited amplifier. 1.5 Specified TSS test conditions: a. Electrode voltages. b. Electrode currents or ranges of current. c. Frequency of operation. d. Value of grid resistor. e.
Driving power if required (if no wattmeter exists, the grid or cathode current and a specified grid or cathode resistor, respectively, can be used as the driving condition). 2. Internal insulation (when specified on the individual TSS). At the conclusion of the power-oscillation test of the highest frequency specified on the TSS and with operation at approximately the same frequency, the anode voltage shall be increased 10 percent and the circuit readjusted to obtain the same anode input. The grid drive may be reduced but the power output shall be not less than that specified for the referenced oscillation test. The tube shall then be operated for 1 hour under the above conditions.
During this period, the insulating material used within the tube should not become overheated as indicated by reddening, nor shall any electrical breakdown occur within or upon the surface of such insulation. At the end of this test, the emission and power output shall be within the limit(s) specified for the referenced oscillation test. METHOD 1236A METHOD 1236A 1236-1 13 February 1974