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HP 8594E Spectrum Analyzer. At last I own a decent Spec An.

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tkamiya:
As to OVEN COLD, it's on TIMER!  It is not actually measuring anything, like OVEN temperature.  It will simply count few seconds since power has been applied.  I don't remember how many minutes but this is in manual.

REF UNLOCK is bad.  When OVEN is fully warm, this error should not be coming on.  As mentioned, it's either loop back connector on back panel is missing, xtal oscillator wildly unstable, or something really really bad.  (like YIG not working)  Personally, I wouldn't buy one without having explanations on why.

TerraHertz:

--- Quote from: tkamiya on January 24, 2019, 01:13:21 am ---As to OVEN COLD, it's on TIMER!  It is not actually measuring anything, like OVEN temperature.  It will simply count few seconds since power has been applied.  I don't remember how many minutes but this is in manual.
--- End quote ---
Reading the service guide, I see you're correct.


--- Quote ---REF UNLOCK is bad.  When OVEN is fully warm, this error should not be coming on.  As mentioned, it's either loop back connector on back panel is missing, xtal oscillator wildly unstable, or something really really bad.  (like YIG not working)  Personally, I wouldn't buy one without having explanations on why.

--- End quote ---
Ah, don't scare me like that. Yep, service guide pg 649 goes into drama-land unless the cause is a missing back panel jumper. I remembered mine _has_ the jumper, so was breaking out in a sweat. But then I checked the screen shots of mine and it says FREQ UNCAL not REF UNLOCK.   Service Guide pg 638 suggests the most likely cause is a flat battery and the machine is running with default cal data. Just needs a new battery and to run the CAL FREQ routine. (And the rest of self-cal. An adventure!)
Wish I'd looked that up when haggling, could possibly have got a few more dollars off the price. Nevermind.

tkamiya:
It would be nice if error message was more in plain language.  "Dead Battery" is much more useful information.  You'll have the same error message if your battery runs out on signal generator HP8644.

It must be an HP thing.

kirill_ka:

--- Quote from: TerraHertz on January 23, 2019, 11:25:44 pm ---Re incomplete GPIB 'CAL DUMP'. Gee, it's almost like they deliberately laid a trap, knowing some users would assume CAL DUMP did something useful. Then would end up sending the instrument back for some very expensive HP attention, after they found they didn't actually have a workable calibration backup. But no, I can't imagine a corporation doing something sneaky and profit motivated like that. (Yes I can.)

--- End quote ---

856XE analysers use EEPROM to store the calibration data.  I think it dates from older 8563A design. There's also
a jumper which prevents changing the calibration.
I wonder why they decided to keep it in SRAM for 859X. Maybe they got tired of opening the case to set the jumper and got rid of that procedure and the EEPROM altogether?

TerraHertz:
You're not being paranoid enough. Maybe they got sick of machines just keeping on working indefinitely? As opposed to getting flat battery, with deliberately obscure error message and many customers giving up at that point and BUYING A NEW MACHINE.

There is a warning message listed:
  USING DEFAULTS self cal needed (U)
  Indicates that the current correction factors are the default correction factors and that the CAL FREQ &AMPTD routine needs to be
performed.

But that's not very direct. Why not "CAL DATA LOST. Replace battery"  The machine knows when it's lost the cal data (presumably via a block checksum fail) because it switches to using a default set of cal data. But does it give you a simple, to the point warning about that? Apparently not.

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