Agilent Technologies 856290216 service manual KHz and 10.7 MHz if Filters, MHz Vcxo

6.Set the HP 8566A/B as follows:

Center frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.7 MHz Span . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2kHz Reference level . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +lO dBm Sweep . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Single

7.Press TRACE A [CLEAR-WRITE) on the HP 8566A/B.

8.Trigger a sweep on the signal generator and on the HP 8566A/B simultaneously. The HP 8566A/B should display a 3 dB bandwidth of approximately 500 Hz.

9.Reconnect W27 (coax 3) to A5J5 and W29 (coax 7) to A5J3.

4.8kHz and 10.7 MHz IF Filters

1.On the HP 85623 spectrum analyzer, press [PRESET), (-1, 300 (K], [El, 600 [Hz), a, and IF $DJ OFF.

2.Disconnect W29 (coax 7) from A5J3. Set the signal generator for a 10.7 MHz signal at -60 dBm and connect it to A5J3.

3.Fine tune the frequency of the signal generator to center the signal on the HP 85623 spectrum analyzer display. Set the signal generator to sweep one 2 kHz span about this center frequency.

4.On the HP 85623 spectrum analyzer, press [WSVVP).

5.Set the HP 8566A/B to 4.8 kHz center frequency and 2 kHz span.

Caution Damage to the HP 8566A/B results if a dc block is not used. The

HP 8566A/B and many other spectrum analyzers have dc-coupled inputs and cannot tolerate dc voltages on their inputs.

6.Connect the VIDEO OUTPUT ( rear panel) of the HP 85623 spectrum analyzer through a 20 dB attenuator and dc block to the input of the HP 8566A/B. Set the sweep time of the HP 8566A/B to 10 seconds.

7.Set the HP 8566A/B to single trigger and press TRACE A (CLEAR-WRITE].Trigger a sweep on the HP 8566A/B and on the signal generator simultaneously. The HP 8566A/B should show a 3 dB bandwidth of 600 Hz flO0 Hz.

8.Reconnect W29 (coax 7) to A5J3.

10.8952 MHz VCXO

Refer to function block E of A4 Log Amplifier Schematic Diagram (sheet 2 of 4) in the

HP 8560 E-Series Spectrum Analyzer Component Level Information.

The purpose of the 10.6952 MHz voltage-controlled crystal oscillator (VCXO) is to provide an LO for down-converting the peak of the 10.7 MHz IF filter passband to 4.8 kHz. Since the peak of the passband of the 10.7 MHz IF filters is 10.7 MHz f300 Hz, the frequency of the VCXO is between 10.6949 MHz and 10.6955 MHz. This frequency can best be measured at the collector of A4Q202.

9-16 IF Section