Products > Test Equipment
HP8595E spectrum Analyzer: readings at -40dB and CAL SIGNAL NOT FOUND
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MarkL:
So sorry you went through the trouble of trying to remove the RF section, and if I said something that implied to do it.  As you are discovering, it's an involved procedure.  I was trying to leave that as a last resort and eliminate all other possibilities first.

More explicitly, and perhaps you can still do this, disconnect the hard coax going to the top of the attenuator (that's the attenuator out) and run an SMA jumper from the attenuator to your Rigol SA.  The attenuator and whole RF section can stay in place.  Then apply your signal generator to the 8595E input and exercise the attenuator as previously described.  See photo.

As for taking the RF section out, it's likely your attenuator is bad and you will have to do this anyway, but my advice would be to take a lot of photos during the disassembly so you will have a record of the cable routing.  (Be thankful you don't have the tracking generator in there too; it's like sausage getting it back together.)

In addition to the instructions in the Assembly Repair Guide (link above from rf-loop), I've also found that removing the screws holding the front panel in place (qty 5 on the sides) and pulling the front panel forward an inch or two will give you a little more working room.  Be sure to disconnect the hard line coax going to the front panel N connector before moving the front panel.
MarkL:
I would also reinforce rf-loop's concern about DC on the input, and NOT use a DMM to check the resistance.

In order to do a DC resistance check, you need to disable the DC block in the attenuator which is on by default in the 8595E (under AMPLITUDE --> COUPLE DC).  But by doing so you would expose the RF input stages to a DC voltage from the DMM, and possibly damage components there.  Don't do it.

If you really wanted to do a resistance check, disconnect the attenuator output from the RF section (as in the above photo), and put a 50 ohm terminator on the attenuator output.  But because you have a signal generator and another SA, a signal test as previously described is a better confidence test.

EDIT: Doing a resistance check from the front connector is not what DavidAlfa was describing, but since we already had one misunderstanding I want to make sure the point about DC is clear.
DavidAlfa:
I said doing so between the input and output of the attenuator, which means both sma connectors removed, completely isolated from the analyzer RF input, so no risk of any kind.
MarkL:
Thanks for posting the CAL DATA DISPLAY.  I'm not an expert on every number in here, but nothing jumps out at me that says the calibration data is invalid.  The AMPLITUDE table looks ok.

The last frequency and amplitude cal is showing as August 11, 2013.  Is that about right?  Has this unit been unused for 10 years?
MarkL:

--- Quote from: DavidAlfa on December 12, 2023, 03:16:59 pm ---I said doing so between the input and output of the attenuator, which means both sma connectors removed, completely isolated from the analyzer RF input.

--- End quote ---
Yes, I did not mean to say your check was erroneous.  I already edited my post after realizing it could have been interpreted that way.
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