Chapter 11 589
RF Section
A7 LODA (LO Distribution Amplifier)
A7 LODA (LO Distribution Amplifier)
NOTE YTO unlock errors may occur if the power delivered to the A15A2
Sampler is less than −9.5 dBm. Frequency response will be degraded in
both internal and external mixing modes if the output power is low or
unleveled.
Error 334 may be displayed if the LO OUTPUT connector on the front
panel is not properly terminated into a 50 Ω termination.
CAUTION Connecting or disconnecting the A7 LODA bias with the LINE switch on
will destroy the A7 LODA. Always press
LINE to turn spectrum analyzer
off before removing or reinstalling W12 to either the A7 LODA or
A14J10.
1. Press
LINE to turn spectrum analyzer off. Disconnect W12 from
A14J10.
2. Connect a jumper between A14J10 pin 5 and A14J19 pin 6. Connect
a jumper between A14J18 pin 13 and A14J18 pin 1.
3. Connect the positive lead of a DVM to A14J18 pin 14, and the
negative lead to A14J18 pin 6.
4. Press LINE to turn spectrum analyzer on.
5. The voltage measured on the DVM should be more negative than
−9.4 Vdc.
6. Move the jumper from A14J18 pin 1 to A14J18 pin 2. The voltage
measured on the DVM should be more positive than +12.3 Vdc.
7. If the voltages do not meet the limits listed in steps 5 and 6,
troubleshoot the A14 frequency control assembly.
8. Connect the positive DVM lead to A14J10 pin 1.
9. The measured voltage should be approximately +5 Vdc. If the
voltage is not +5 Vdc, troubleshoot the A14 frequency control
assembly.
10.Connect the positive lead of a DVM to A14J18 pin 15. The voltage
should measure within ±10 mV of the GATE BIAS voltage listed on
A7 LODA label.
11.If this voltage is not within the correct range, refer to "LO
Distribution Amplifier Adjustment" in Chapter 2, "Adjustment
Procedures."
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