Downloaded from https://www.everyspec.com MIL-STD-1311D METHOD 2204B (Single-Sideband) 1. Purpose. To measure the power output (normally up to 32 MHz) of a linear amplifier with one or two-tone input signals and to measure the intermodulation distortion with two-tone input signals. 1.1 General. 1.2 Procedure 2.1 shall be used for 1-tone power output measurement and 2-tone IM distortion measurement. Procedure 2.2 shall be used for 2-tone power output measurement and 2-tone IM distortion measurement. Procedure 2.1 or 2.2 may be specified. These are grounded cathode tests. 1.3 The following shall be specified on the TSS: a. DC voltages applied to the tube elements. b. Maximum value for Rg. c.
Value for R , with tolerance. d. Value for anode loaded tank Q, with tolerance. e. Idling anode current (Ibo) with no rf drive applied. f. One tone and/or two tone rf drive level to be applied (in terms of setting for specified grid current, peak grid/cathode voltage (egk), power output, or other as applicable). g. Minimum or maximum time to be held under the specified test conditions, if applicable. h. Which odd-order IM distortion products are to be measured (3rd, 5th, etc.). 1.4 The test shall be performed using the basic circuit shown on figure 2204-1. a. All circuit components, circuitry, layout, construction, and metering shall be in accordance with good engineering practice. b.
The filament voltage meter and the dc meters used for measuring current and voltage in the grid circuits and the anode circuit, shall be calibrated for 1.0 percent accuracy or better. All calibrations shall be referred to the TUT socket. c. The rf test frequency range used shall be specified on the TSS. d. The IM distortion of the (two-tone) SSB signal source shall be at least 10 dB better than the corresponding IM limit on the TSS, but never worse than -55 dB. The two tones shall be equal in amplitude, with a tone separation of 1,000 to 2,000 Hz. If audio tones are used to initiate the signal, they shall not be harmonically related. e.
All power supplies except the anode shall be electronically regulated to 1.0 percent or better for line/load variations. f. IM distortion shall be measured with a high-quality spectrum analyzer, or equivalent, referencing only one tone of the two equal-amplitude signals making up the (two-tone) composite signal. The TSS limit(s) shall be interpreted to mean that the maximum amplitude of the IM products shall be the specified number of dB or more below the reference tone. g. Power output shall be considered as useful, delivered to the load, and shall be read with 5 percent accuracy or better.
If power is computed from E2/R, the VTVM used should be a true rms responding and reading instrument or equivalent. h. No negative feedback is to be used in the test circuit in figure 2204-1 except the stage may be neutralized if required for stable operation. If neutralization is necessary, it should be adjusted with no anode current flowing and no further adjustment should be made thereafter. LINEAR AMPLIFIER POWER OUTPUT AND DISTORTION, TWO-TONE METHOD METHOD 2204B 2204-1 25 March 1970