TM 11-6625-2837-14&P-7 TECHNICAL MANUAL OPERATOR'S ...

Section 4 TM 11-6625-2837-14&P-7
PERFORMANCE TESTS
4-13B. OUTPUT ACCURACY - ALTERNATE PROCEDURE (Cont’d)
NOTE
Do not change the RF Section VERNIER Control Setting until this
procedure is completed.
4. Set the spectrum analyzer controls as follows: center frequency 30 MHz, frequency span per division 5 kHz,
resolution bandwidth 3 kHz, input attenutation 10 dB, vertical sensitivity per division 2 dB and sweep time per
division 5 ms.
5. Set the 10 dB Step attenuator switch to the 80 dB range.
6. Connect the equipment as shown in Figure 4-4B.
7. Adjust the reference level range and vernier to extablish a reference level on the analyzer display.
8. On the first line of the following table, record the power meter reading shown on the preceding table for the
OUTPUT RANGE Setting of 0 dBm and the panel meter reading of +3 dB. This is the absolute RF level which
corresponds to the display reference.
9. Set the OUTPUT RANGE switch and the 10 dB step attenuator range switch settings as shown on each line of the
following table. Record the display variation from the established reference.
10. Calculate the RF level using the following formula:
dBm = dBm1 - ΔAdB10 + ΔdB
dBm is the RF output level
dBm1 is the RF level measured at +3 dBm (0 dBm OUTPUT RANGE setting) in step 3.
Δ dB10 is the change in 10 dB Step Attenuator level
Δ dB is the variation from the established display reference for each OUTPUT RANGE setting.
For example, results of the first step are:
dBm1 =+2.8
ΔA dB10 = 10
ΔA dB= -0.2
dBm = +2.8 dBm -10 dB +(-0.2) dB
= -7.4 dBm
4-14