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Agilent E8357A

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joeqsmith:
I am getting a sinking feeling about the source leveling.  Could it be that they were writing directly into the PNAs memory.  I tried some of the SCPI commands to read out the source calibration (not the commands which use the GPIB as the master).   So far I have been able to reliably crash the VNA software and Ethernet connection.   :-DD   
 
I wonder if two different teams worked on the source and receiver leveling.  Maybe that's why they are so different.  They could have had everything stored in their custom MX files.   I bet there are some good stories about the culture within Agilent during this time.     

diag:poke/peek:byte,int&long
SENSn:CORR:CSET:STAT/SEL OFF/ON

joeqsmith:
After unsuccessfully sorting out the source leveling, I decided to take a step back and try a very simple test.   The following is from the programming manual:


--- Quote ---Source:Power:Correction Commands
Controls the source power correction features of the analyzer.

Note: the SOURce:POWer:CORRection:COLLect:ACQuire command, used to step the PNA and
read a power meter, cannot be sent over the GPIB. Use one of the alternative methods described
in the command details.

SOURce<cnum>:POWer<port>:CORRection[:STATe] <ON|OFF>
(Read-Write) Enables and disables source power correction for the specified port on the specified channel.

Parameters
<cnum> Any existing channel number. If unspecified, value is set to 1
<port> Port number to correct for source power. If unspecified, value is set to 1.
<ON|OFF> ON (or 1) turns source power correction ON.
OFF (or 0) - turns source power correction OFF.
Examples SOUR:POW:CORR ON
source1:power2:correction:state off

Query Syntax SOURce:POWer:CORRection[:STATe]?
Return Type Boolean (1 = ON, 0 = OFF)

Overlapped? No
Default OFF (0)

--- End quote ---

While from the description, this would seem to be related to the source's alignment,  I ran another sweep with the power meter attached.   I then sent the SOUR:POW:CORR OFF command.  The PNA flagged no errors or warnings.  I then took another sweep.   As you can see, it has no effect.  So these commands must be for some other feature but not the alignment.

caesarv:
For the early PNAs, such as the E835xA, the source adjustment values are stored on the individual boards in EEPROM.  Most boards have a 512 byte EEPROM (not kB!)  This, of course, is not much memory but it is enough to store values for each band.  The receiver (mixer) cal had too much data, so it had to be stored in files on the HDD.  Later PNAs had large flash memory on the Test Set Mother Board and that was used whenever data had to be stored....with a few exceptions.
The EEPROM on each board is divided up into a Header (16 4-byte values) and the remainder. 

You can look at the contents of this by running the ViewEEHeaders program.  It will show the headers and the data.  You can even edit those values, although I do not recommend doing so.  Changing some values can really (and hopelessly) screw up operation.  There is a way to store all the data to a backup files....I suggest doing that. 

joeqsmith:
FYI, this program requires a password.  I assume it uses blank, agilent or tsunami.  Mine is tsunami.   Using the View, Minimize Application, we can see a program called EEBACKUP.EXE located in the service directory.   It appears the PNA software must be running.   Selecting the Backup EEPROM causes a crash. 

Ignoring the backup and looking at the contents of the source board, it's not at all what I would expect for a precise leveling adjustment.   I wonder if these hardware adjustments are separate from the leveling adjustments.   Or, maybe you can't actually get the source anymore level than what I have shown.   

I would have guessed that they wanted to be able to send out a replacement board and not have to deal with send the data on a separate media.  If you still had to send the instrument in for alignment anyway, this really makes little sense.   

joeqsmith:
Oddly enough, it recovers?   A new menu is then displayed.   My system sits on the LAN, making it easy to transfer files.  Once you get the save and completed message the software creates 4 files.   Interesting if they have these recrcal12&21 files which are different than the MX files.   All 4 files are ASCII.   I have attached the EEPROM.DAT file from mine (renamed to .TXT).

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