Hi All,
Happy new year to everyone.
I have a 8593E that has a Local un-level issue. While checking the LODA Gate Bias using the service level procedure, the DMM reading was around -1.29V and all over the place by as much as several hundred millivolts.
The RF assembly Gate bias sticker states -700mv, I adjusted R29 as stated and the GB level can be adjusted down to the desired -700mv, however the voltage is still quite unstable, again as much as +/- 100mv, whereas the process states that the adjustment must be within 5mv.
I have never worked on any 859x series SA before,, could this symptom be a power supply issue, or is there a more sinister/serious non serviceable fault?
Would anyone have recently checked the LODA GB voltage?
The Analyser functionally works very well. However a basic phase noise measurement using John's GPIB toolkit showed a serious measurement error compared to my HP8560E using both internal ref signals.
Thank you in advance.
Regards
Gerald
VK3GJM
