Electronics > Repair
Agilent PSA E4440A spectrum analyzer: LO1 unlock
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matthieu.e:
Hello,

I am trining to fix a Agilent E4440A 26.5 GHz spectrum analyzer. I will post here the repair avancement.

Any help will be appreciated on this repair. Thank you  :-DMM   :-+

First inspection:

The SA boot but I have two type of error :
- "1st LO unlock"
- "1st LO unlock, Failure to acquiring single loop FracN LO loop"



If I lower the SPAN down 2 MHz, the SA stop sweeping. For a SPAN value > to 2 MHz it start to sweep again.

To investigate I have a generator up to 3GHz another SA (not the same) and a scope.

The schematic and service manual can be find here :

https://www.testworld.com/wp-content/uploads/service-guide-keysight-agilent-e4440a-e4443a-e4445a-e4446a-e4447a-e4448a-spectrum-analyzers.pdf

https://www.keysight.com/us/en/assets/9018-04012/service-manuals/9018-04012.pdf?success=true





matthieu.e:
Here is the E4440 block diagram

matthieu.e:
Just got the result for the A18  YTO output. I insert a coupler to mesure to rf sweep.

The spectrum analyzer sweep from 10 MHz to 26 GHz.

I was forced to increase the sweep time to be able to mesure it with my spectrum analyzer.

Sweep frequency span seems to be OK. Output power is approximately 15 dBm.

The YTO seems to be OK.

What should I look at next ?
matthieu.e:
Looking at the A21 SLODA unit (LO distribution amplifier)

The "first LO out" port seems to be OK. Same response than the YTO and 13 dBm output signal.





The "LO band output" seems to be OK. 3.8 to 6 Ghz frequency response with 14 dBm output power (don't know why it doesn't go up to 7GHz for the Lo band)

 

 

The "HI band output" seems to be OK. 3.2 to 6 Ghz frequency response with 14 dBm output power (don't know why it doesn't go up to 7GHz for the HI band)





Need to look at the "Sampler output", I will do it later.
matthieu.e:
Now I will look at the A20 low band unit



I applied a 800 MHz (-18 dBm) signal at the input of the spectrum analyzer

Looking at J1, input port of the A20 board, signal is here at -40 dBm. That seems OK



Looking at J7, output of the A20 board, the signal is strange. I should normally get a 321.4 MHz IF signal at -43 dBm. What do you think ?  :-//

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