TM 11-6625-2781-14&P-2
TEST PROCEDURE
SERVICE SHEET 9
Connect the HP 8405A and the HP 5245L/5252A thru
It is assumed that there is no 50 MHz input to the 50
the 50 Ohm Tee to TP A (A10J2) and observe the
MHz IF Amplifier and that the -10 Vdc operating voltage
indications. The instrument readings should show a 150
and 200 MHz IF input are both present.
MHz signal at approximately 200 MHz rms. If the correct
indications are not obtained, check Q1/Q2 and
TROUBLESHOOTING PROCEDURE
associated components.
When the cause of malfunction has been isolated to the
Second Converter Assembly it should be removed from
If the correct indications are obtained, proceed step 3
the casting and installed in an inverted position using the
fasteners provided in the Service Kit to provide access to
components. Test procedures follow the discussions of
4
SECOND MIXER
individual circuits.
The second mixer accepts the 200 MHz IF signal and the
EQUIPMENT REQUIRED
150 MHz local oscillator signal and mixes them to
Service Kit . ....................................... HP 11592A
produce a difference signal of 50 MHz containing all of
Frequency Counter ................... HP 5245L/5252A
the modulation components appearing in the 200 MHz
Vector Voltmeter................................. .HP 8405A
input signal. The 50 MHz output of the mixer is coupled
50-ohm Tee ....................................... HP 11536A
from the secondary of T3 thru balun T4 to the processing
CONTROL SETTINGS
circuits in the IF Section.
SCAN WIDTH ...........................................ZERO
INPUT ATTENUATION. ............................... 0 dB
TEST PROCEDURE
FREQUENCY .......................................... 30 MHz
CAL OUTPUT........ connected to RF INPUT PUT
Connect the HP 8405A and the HP 5245L/5252A thru
the 50 Ohm Tee to TP B (A10J1) and observe the
1
200 MHz IF BANDPASS FILTER
indications. The instrument readings should indicate a
50 MHz signal at approximately 70 mVrms.
Signals from the 200 MHz IF Bandpass Filter are down
converted to 50 MHz by the second converter. The input
If the correct output is obtained, Second Converter A10
signal is mixed with a 150 MHz signal to obtain a 50 MHz
is functioning properly.
IF signal containing the modulation components of the rf
input. The amplitude of the 50 MHz IF signal is
If the correct output is not obtained, first tune t, 8553B
determined by the amplitude of the input rf signal.
FREQUENCY control to assure that the analyzer is
Conversion loss is approximately 7 dB.
tuned to the calibrator signal, then check the mixer circuit
components, and repeat the test.
Figure 8-43. Simplified Diagram of
Second Converter.
2
150
MHz LOCAL OSCILLATOR
Simplified Test Procedure Tree
The 150 MHz crystal controlled local oscillator provides
The following components are factory selected
two outputs. One output drives CR1 thru CR4 in the
components. Values shown are nominal. Actual value is
double balanced mixer; the other is applied to auxiliary
selected at time of final test inspection.
output Jack J2.
L4 is selected for compatibility with other circuit
components.
R5 is selected to provide gain compensation.
8-40
