HP 8590A spectrum analyzer operational/behaviour question

[prutser]

I have an HP8590A and I wonder if my understanding is wrong or the unit has some problems.

If I apply a signal of +5dBm at the input then (default level settings after preset button) then the to of the signal is outside the grid. (att setting 10dB)
I would expect to increase att level, but when I increase the att level, the signal remains the same, but the noise floor goes up. (I hear the att relais clicking)

Does somebody knows if this normal behaviour ?


 

[coppercone2]

I have this model right here, when you increase the attenuation the peak stays at the same level and the noise floor moves up or down. if you want to change the scale try the db/division

what is your mixer level set to?

Keep in mind, once you have the amplitude menu open, and you select a function, you need to press the amplitude button to get into reference level again, it does not have a side menu option  for it (appears to be a hidden setting). Perhaps you are confused and messing with the mixer rather then the reference level button when you are navigating the menu.

Amplitude button = reference level by default
right side menu = atten, log, lin, mixer level, ref level offset. no option for the reference level, so you need to hit amplitude again. Don't ask me why, there is a blank button that could bring you to the reference level prompt, oversight I guess.

Now if you mess with mixer level, and you notice its not moving down after you move it up, you need to click on amp to get mixer level to bring it down (it makes it track up). The other menus don't do this. FRQ and SPAN stay in the same right side window so its just hotkeys, but amp is a unique setting (reference level) only brought up by amp. I don't know if its accessible from another menu I forgot about.

[prutser]

Thanks for the reply. My mixer setting is at its default -10dBm. Actually I also tried ref level offset (was expecting to change ref level, but could not find a ref level option)
but it didn't do much. But your reply triggered something for me... when pressing the Amplitude button you're actually in the "ref level" setting. I was looking for
something like this in the side menu after pressing the "amplitude" button. But it's missing there. 
Now it makes sense 

[coppercone2]

yea i dunno why its not there on the right side lol

just be sure to check the settings sometimes like the mixer level if you change one it changes the other ones but it does not back track so you need to navigate into other menus to adjust them, it might do this with video bandwidth and stuff.. the more advanced hp analyzers (and maybe this one too, but keep in mind this is designed with field use in mind a bit) let you select if the settings track and ratios at which they track and stuff like that

Now its kinda hard to imagine this being a field instrument because you have compact lithium ion handhelds with similar specifications for the common tests, at least if you have a corporate budget they make more sense..