Table 12-2. TAM Tests versus Test Connectors

Connector Manual Probe Troubleshooting Test Measured Signal Lines

 

A14J16

YTF Offset DAC

 

 

MS6

 

 

YTF Gain and Offset Input

MS2

 

 

YTF Gain DAC

 

 

MS1

 

 

YTF

Drive

 

 

 

 

MS3

 

 

Band Switch Driver

 

MS8

 

A14J17

Main Coil Coarse DAC

MS3

 

A14J18 L O D A D r i v e

 

 

 

MS5, MS6, MS7, MS8

 

A14J19

Second

Conv

PIN

Switch

MS8

 

 

Second

Conv

Mixer

Bias

MS1

 

 

Second

Conv

Drain

Bias

MS3

 

 

Second

Conv

Doubler Bias

MS4

 

 

Second

Conv

Driver

Bias

MS5

 

 

First

Mixer

Drive

Switch

MS7

 

 

First

Mixer

Drive

DAC

MS6

 

A14J302 R e v i s i o n

 

 

 

 

MS7

 

 

A15J400

IF AMP/Limiter Bias

MS6

 

A15J502 Third LO Tune Voltage

MS3

 

 

3rd LO Driver Amp

 

MSl, MS8

 

A15J602 SIG ID Collector Bias

MS7

 

 

RF Gain Control Test

MSl, MS3

 

A15J901 R e v i s i o n

 

 

 

 

MS3

 

 

External

Mixer Switch

MSl, MS8

 

 

Signal ID Switch

 

 

MS5, MS6

 

 

External

Mixer Bias

 

MS7

Low Band Problems

1.Disconnect all inputs from the front-panel INPUT 50R connector.

2.Set the HP 85623 to the following settings:

Center frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 Hz Span . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..lMHz Input attenuator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 dB

3.The LO feedthrough amplitude observed on the display should be between -6 and - 3 0 dBm.

Note

The marker will not PEAK SEARCH on the LO Feedthrough when in a

non-zero span. To measure the LO Feedthrough amplitude with the markers,

set the SPAN to 0 Hz and CENTER FWQ to 0 Hz. Press (MKRI ON.

4.If the LO feedthrough amplitude is within limits, but signals are low, the RF path following the A8 mixer is probably operating properly.

12-4 RF Section

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Agilent Technologies 856290216 service manual Low Band Problems, Pin