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Azur Electronics

OPERATING HP 8553B
RF SECTION
CALIBRATION 
 
Before the Spectrum Analyser can be used, it must be calibrated using the following procedure.  This sets the HP 8552B IF Section X & Y gain & position and the HP 8553B RF Section amplitude calibration.  
[Based on HP 8552B & 8553B Operating and Service Manuals]

NOTE: Ensure the 8552B / 8553B D-type connectors are correctly mated. 
Poor mating is often the cause of X & Y display problems! A quick check is to ensure that switching the INPUT ATTENUATION lights all the lamps around the LOG REF LEVEL control. 


1. Initial Setup
 
Switch HP 141T Display Section LINE ON. 
Press NON STORAGE mode CONV button.
Intensity to 12 o’clock approx. 
Focus to 12 o’clock approx. 
Allow to warm up for 30 minutes approx. 
 
Set 8553B Controls as follows: 
RANGE MHz 110MHz 
FREQUENCY 40MHz 
FINE TUNE Centred 
BANDWIDTH 300kHz 
SCAN WIDTH 0-100MHz 
PER DIVISION 10MHz 
INPUT ATTENUATION 10dB 
TUNING STABILIZER On 
 
Set 8552B Controls as follows: 
MANUAL SCAN Centred 
BASELINE CLIPPER CCW 
SCAN TIME PER DIVISION 5ms 
LOG REF LEVEL 0dBm 
LOG REF LEVEL Vernier 0 
LOG LINEAR 10dB LOG 
VIDEO FILTER 10kHz 
SCAN MODE INT 
SCAN TRIGGER AUTO

2. Focus and Astigmatism  
 
Adjust INTENSITY as needed.  
 
Set LOG REF LEVEL maximum CCW (this minimises noise on the baseline).  
 
Adjust VERTICAL POSITION to set the trace to the -50dB graticule line.  
 
Set SCAN TIME PER DIVISION to 10s.  
 
Adjust FOCUS and ASTIG for the smallest round dot possible.  
 
3. Trace Alignment

Set SCAN TIME PER DIVISION to 5ms.  
 
Adjust TRACE ALIGN to set the trace parallel to the horizontal graticule line.  
 
4. Horizontal Position and Gain  
 
Adjust HORIZONTAL POSITION so the display is centred on the CRT.  
 
Adjust HORIZONTAL GAIN so the displayed scan width is exactly 10 divisions on the CRT.  
 
Some interaction between HORIZONTAL POSITION and GAIN controls may require readjustment.


The zero frequency 1st L.O. feed through at 0MHz
and Marker below the trace at 40MHz
5. Vertical Position and Gain  
 
Adjust VERTICAL POSITION to set the trace to the -80dB graticule line.  
 
Set LOG REF LEVEL to 0dBm.  
 
Set FREQUENCY to 50MHz.

Connect 8552B CAL OUTPUT to 8553B RF INPUT using a BNC to BNC 50Ω coax cable. 
 
The zero frequency 1st L.O. feed through at 0MHz. 
The Calibration Signal at 30MHz and -30dBm. 
The 2nd harmonic at 60MHz and -40dBm. 
The 3rd harmonic at 90MHz and -50dBm.
The inverted marker below the horizontal base line indicates the centre frequency of the SCAN WIDTH – PER DIVISION and ZERO tuning modes.

Adjust FREQUENCY to place the marker under the Calibration Signal at 30MHz and achieve maximum null.

Set SCAN WIDTH to PER DIVISION and .05MHz.

Set BANDWIDTH to 10kHz.
 
Adjust FREQUENCY FINE TUNE to centre the signal on the CRT. 
 
Adjust LOG REF LEVEL and VERNIER so maximum signal amplitude is exactly on -70dBm graticule line.

Rotate LOG REF LEVEL 7 steps clockwise. The amplitude of the signal should increase one vertical division per 10dB step.
 
Adjust VERTICAL GAIN to place maximum signal amplitude exactly on the top graticule line.

Repeat the previous 3 steps to obtain optimum setting. 
 
Display shows Calibration signal at 30MHz  
Note noise on baseline
6. Amplitude Calibration 
 
Set LOG REF LEVEL to -30dBm.
 
Adjust AMPLCAL to place maximum signal amplitude exactly on the top graticule line. 
 
The Spectrum Analyser is now calibrated in the LOG display mode from -130dBm to +10dBm. 
 
7. Linear Mode
 
Set LOG REF LEVEL to 1mV/DIV on blue scale.

Set the LOG – LINEAR switch to LINEAR. 

 Set LINEAR SENSITIVITY to 1mV (Vernier 0 position).

Display showing the 30MHz calibration signal at 7.1mV

The left hand side vertical graduations 0 to 8 are calibrated in absolute voltage. 
 
Maximum signal amplitude should be 7.1mV, if necessary adjust AMPL CAL to achieve this. 
 
The Spectrum Analyser is now calibrated in the LINEAR display mode from 0.1µV to 100mV. 
 
8. Reset

Return the 8552B and 8553B controls to their starting position. 



NOTE: Maximum RF Input level is +13dBm, 20mW, 2.8Vac peak to peak, 1V rms, ±50Vdc. To avoid damage to the Mixer, initially utilise maximum input attenuation and/or an external attenuator!