Hi Yves,
Thanks for your reply. My units 53181A and 53132A are both HP models not
the newer Agilent ones. Both were basic versions without OCXO and
without 2nd channel for 53181A and 3rd channel for 53132A.
I built my own OCXO boards and I wanted for some time to add the extra
channel.
I have some PLCC sockets so I will attempt to remove the EEPROM.
You were lucky with your units because some people reported they didn't
have in the EEPROM header written 'HP53131 is a winner!' so those will
not work to add the 3rd channel unless firmware is upgraded.
For calibration you will need the following:
1) 10MHz source
2) precise 5V reference source
3) pulse generator
4) time interval calibrator (J06-59992A)
Someone on EEVblog made a board to replace the parts from points 2-3-4.
He says he sells the kit for $30.
Thanks,
Razvan
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On 07/05/2024 02:42, Yves Tardif via groups.io wrote:
Hi Razvan,
When you have a 5313xA firmware 3403, I think by default the EEPROM includes the configuration for the 3GHz option.
So, only the hardware option would be missing.
When I bought my hp53132A several years ago, I installed the 3GHz option only later.
After installing the PCB, the 53132A worked normally without having to modify the EEPROM or adjust the scale.
Since then, I have acquired another meter, Agilent 53132A (newer, firmware 3944); I transferred the 3GHz option to this one without problems and the frequency displayed was normal, without having to put a compensation scale or modify the EEPROM.
Hence my conclusion that the 3GHz option is activated in the EEPROM by default, but it obviously requires the hardware part to be added.
The 124 option (12.4GHz), the divider is 512 instead of 128 for 3GHz, then you must put a scale of 4, to multiply the result by 4 to display the correct frequency.
By modifying the EEPROM as suggested in the document, I should be able to make the 12.4GHz option work without changing the scale.
It's quite easy to simply activate the scale at 4.
But in my opinion, it may be a lot of work and a risk to remove the EEPROM, put a socket (restricted place on the PCB), and make modifications in the EEPROM.
Furthermore, on the PCB of my hp53132A, I cannot find the R334 resistor cited in the document.
In short, I will look at the implications of making this change, and I will take the opportunity to do a firmware update, if I decide to move forward with this little project.
I need to check the calibration procedure first.
Yves
