Low Band Problems - Agilent Technologies 8564EC Service Manual

Low Band Problems

1. Disconnect all inputs from the front panel INPUT 50Ω connector.
2. Set the spectrum analyzer to the following settings:
3. The LO feedthrough amplitude observed on the display should be
The marker will not PEAK SEARCH on the LO Feedthrough when in a
NOTE
non-zero span. To measure the LO Feedthrough amplitude with the
markers, set the SPAN to 0 Hz and
ON.
4. If the LO feedthrough amplitude is within limits, but signals are low,
5. If the LO feedthrough amplitude is higher than −5 dBm (signal will
6. If signal amplitudes <2.9 GHz are bad, but signals >26.8 GHz are
7. Perform the steps located in
8. Check A13 second converter mixer diode bias at A14J19 pin 1. The
9. Troubleshoot the signal path. Refer to the power levels listed on
Chapter 12
Center frequency .......................................................... 0 Hz
Span .......................................................................... 1 MHz
Input attenuator ........................................................... 0 dB
between −6 (above top of screen) and −30 dBm.
the RF path following the A8 mixer is probably operating properly.
be "clipped" at top of screen) and signals are low in amplitude,
suspect a defective A8 mixer assembly.
good, check the A8 Low Band Mixer or the filter FL1. If both the LO
feedthrough and signal amplitudes are low, check the A12 SBTX.
Drivers" on page 615.
bias voltage should be between −150 and −800 mVdc.
Figure 12-11 on page
Diagram.
CENTER FREQ
"Control Latch for Band-Switch
631, RF Section Troubleshooting Block
RF Section

Low Band Problems

to 0 Hz. Press
MKR
599