HP 11793A manual Device

Microwave Converter Model 1 1793A

RF Devices (Service Sheets 1 and 2)

Because of the diversity of test equipment and techniques available for troubleshooting the high-frequency devices, no specific procedures are given. Check the performance parameters of the RF devices against the following table, Table 10.Also check connectors and cables.

	Table 10. Performance Parameters
Device	Performance Parameters to Check

AT1	Attenuation: 2.5 to 3.5 dB at 18 GHz
3 dB	2.0 to 4.0 dB at 26.5 GHz
Attenuator	SWR: 4.251 at 26.5 GHz~~
FL1	3 dB Corner: 900 to 1100 MHz
Low-Pass	Passband Insertion Loss: <0.25 dB at
Filter

~~

800MHz

s1, s2 Insertion Loss: 4 . 5 dB at 26.5 GHz

Switch SWR: <2.0:1 at 26.5 GHz

u1 Frequency Range: 18 to 26.5 GHz

LOGain: >11 dB

Amplifier SWR: C2.51

u2 Frequency Range: 10 to 700 MHz

IF Gain: 14 dB

Amplifier SWR: <1.8:1

u3 LO Frequency Range: 2 to 26.5GHz

Mixer RF Frequency Range: 1.3 to 26.5 GHz LO Power: >+8 dBm

Conversion Loss: <lo dB

SWR: <4:1

Control Devices (Service Sheet 3)

Set a power supply to 0 Vdc and connect it to the FREQ OFFSET INPUT connector. Set the supply to 0, +3, and +S Vdc respectively, and compare the logic levels of the logic devices with those listed in Table 9. When specifically checking the drive transistors 42, Q3,Q4, or QS, note the following:

The switch solenoids automatically disconnect after completion of switching. Therefore, it is difficult to distinguish between a drive transistor that is on but not drawing current, or one that is off and not drawing current. The collector voltages will differ by only a few mV. If any of the transistors are known to be working, compare the on and off voltages of the suspected transistor against those of a known good one.

Power Supplies (Service Sheet 3)

Check the points indicated in the schematic diagram for dc level and ac ripple. Note that the +SV Regulator is dependent on the + 12V Regulator.

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