I have an HP 8591c which had the default CATV personality installed by HP and the SPECAN operation was fully-functional, passing all self-tests. The instrument also has Opt 130 - Narrow BW – installed.
In a moment of stupid inattention, incorrect front-panel keys were entered causing the DLP memory contents to be erased. This resulted in the CATV personality ‘disappearing’, leaving only the SPECAN function seemingly operational.
While I could live without the CATV personality, the DLP erasure also removed other important SPECAN links. Now only the narrow RBW (30Hz, 100Hz & 300Hz) function and show a correct trace. Any other RBW settings result in no display.
Inspecting the Service Manual shows the Narrow BW card (A130) contains a MUX switch that routes the 21.4MHz IF signal to/from the following A14 Log Amp/Detector card. At first glance, it seems the MUX is now missing the appropriate commands due to DLP erasure. I have not tried removing the NBW option A130 card and inserting jumper W1 on A14 as I’d prefer to keep the narrow RBW settings.
Fortunately, I have access to an identical donor machine. Is it possible to export the CATV firmware from the donor machine and re-load it back into my instrument ? If so, would a blank HP memory card be required ? HP memory cards preloaded with CATV personality (HP-85721A) are available from eBay, but I’m unsure whether reloading the CATV personality this way would also restore RBW operation back to normal.
Any assistance gratefully appreciated.
Kit
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