(7) When the optimum gain-bandwidth
setup can be made at any convenient location. Remove
response has been obtained, carefully relock the AT3
2A4 from 2A2 and 2A3 by flipping open the waveguide
attenuator control with the lock thumbscrew while
observing the oscilloscope to make certain that the
2A4 The initial test setup shall contain the item under
locking procedure does not change the control settings
test (2A4) connected to the test equipment, that is, use
and, therefore, the amplifier response.
the Test Connection of figure 3-8 first, connecting 2A4
(8) Reset toggle switch 1S5 to 2ND STG ON
between CN-1367/U and V'G- 1054/U.
c. Test Procedure
per b(7), (8), and (9) above If the response is not
(1) After the test setup is made using Test
completely satisfactory, make minor adjustments by
means of the second stage controls while observing the
(sweep generator and oscilloscope) and permit 15-
channel response on the oscilloscope. Second stage
minute warmup period.
controls are de scribed in (9) through (13) below.
Operational requirement is for adequate channel
frequency band 7.20 to 7 80 GHz. Set frequency
response. How this response is divided between the two
markers at 7.25 and 7.75 GHz Check to see that marker
stages of amplification is irrelevant.
frequencies are correct with FR-194/U.
(9) If the second stage (2A2) characteristics
(3) Set CN-1367/U at 1.0 dB.
are out of tolerance, set toggle switch 1S4 to BYPASS
(4) Set AN/USM-273 for maximum sensitivity
and display the gain-bandwidth response curve on
and obtain a convenient reference trace on the
(5) Remove 2A4 from the test setup and
(10) Perform (3) above (Remove cover plate
make the Test Reference Connection, that is, connect
CN-I 367/U to VG- 1054/U.
(11) Unlock 2A1AT4 attenuator control and
adjust the gain as in (4) above, using the AT4
oscilloscope trace to the reference trace level.
(7) The difference in CN-1367/U settings of
(12) Adjust 2ND STG BIAS control 1R6 (fig. 3-
(4) above and (6) above is the insertion loss of
3) using the procedure in (5) above.
Waveguide Filter Module 2A4.
The loss shall be
(13) Continue the alignment procedure as
between 0.0 dB and 0 3 dB.
given in (6) and (7) above, but using 2A1AT4 and 1R6
adjustments. Stage gain shall be 13.5dB over 500 MHz
(8) Remove the grease pencil trace marks
from the oscilloscope scope face.
band Refer to b(15) above.
(9) Set CN-1 367/U at 25 dB. Obtain a trace
(14) Reset toggle switch 1S4 to 1ST STG ON.
Check the channel gain-bandwidth response as per b(7),
(8), and (9) above. Minor adjustments of this first stage
controls ((4) through (7) above) may be necessary for
frequency band 7.0 to 8.4 GHz. Set frequency markers
optimum channel response.
at 7.1 and 7.9 GHz.
(15) Remove the test equipment and replace
(11) Insert Module 2A4 in the test setup, that
the cover plate (with four Phillips head screws removed
is, between CN-1367/U and VG-1054/U.
in (3) above) on the Pump Source Module 2A1 front
(12) Set CN-1367/U to 5 dB. ((9) setting minus
step in (12) above setting = 20 dB.)
3-8. Waveguide Assembly RF Tests
(13) Observe the oscilloscope for responses in the
a. Assemblies That Can Be Tested. RF insertion
frequency bands 7.0 to 7.1 GHz and 7.9 to 8.4 GHz. No
loss over the amplifier passband (7.5 i 0.25 GHz) can be
response shall reach the reference trace levels set in (9)
measured on any waveguide assembly that can readily
above. The specified filter rejection is 20 dB or more in
be removed from the system. Waveguide Switches 3A2
these two frequency bands.
and 3A3 can be tested in place, if necessary. Other Unit
(14) Remove Module 2A4 from the test setup
3 waveguide assemblies (3A4, 3A5, 3A6, 3A7, 3A8, 3A9,
and reconnect it in Frame Assembly Unit 2 to Modules
3A10, 3AI 1, 3A12) can be removed and tested
2A2 and 2A3.
individually or tested in sections. Refer to paragraph 3-
3-9. Pump Frequency and Power Tests
6b. The procedure given here is specifically for
Waveguide Filter Module 2A4. Any other waveguide
Module 2A1 contains a 1000-V line and a 120- V line Do
assembly (WR 112 size) can be measured by the same
not open the chassis cover.
procedures c(l) through (7) below. The additional steps
in c below are for out-of-band signal rejection tests of the
Do not perform these tests unless gain-band- width tests
b. Test Setup. The test equipment and test setup
apparent cause is inadequate pump power. Refer to
shown in figure 3-8 shall be used except that the item
under test is Waveguide Filter Module 2A4 instead of
Amplifier, Parametric AM-6602/MSC-46(V). The test