Anritsu MS462X / Scorpion Noise Figure measurement

[alan.bain]

I've been trying to make some NF measurements with an Anritsu MS4622 "scorpion" which says that it has the 6GHz NF Option on the HW options screen, but every time I try and measure I get a Noise Figure overload error.  There also seems to be a distinct lack of 28V out of the back port for the HP346B.

I'm wondering if the software is present but some hardware element is not present, although I would have thought the firmware would have detected that.

Photo shows the front of the RF board.  I'm wondering if there should be some other modules behind the input modules marked 46720.

Alan

[DaJMasta]

You want to confirm what hardware you actually have, the 4622 is a 3GHz unit, the 4623 is the 6Ghz version.  I wonder if the CPU board in your unit is from another unit or if some of the stored data has been configured for a different model.  There also should be the 28V BNC on the back for the power supply.

[alan.bain]

There is indeed a socket on the rear for the 28V supply to the noise source.  It is the 3GHz variant (4622) but the BBRAM snaphat has had to be replaced.  I remember this being a painful process, but the screenshot from before I did this shows the Noise Figure option present.

[RFMWdude]

Noise Figure Measurement requires option 4. This should be mentioned on the rear panel.

The A2 Option Module is required for this:


You can set some DIP switches on the CPU board to configure the options (and make the software believe NF Measurements are possible). But without the A2 Option Module present, this obviously doesn't work as expected.

[alan.bain]

Thank you very much RFMWDude that photo makes it clear. There is no A2 option module.  Now that I look at the schematics I see that the noise figure receiver is on this board and as suspected the DIP switches are set incorrectly. Actually rather makes sense since this is a 3GHz VNA and the options available listed 6GHz NF measurement which should have seemed incongrous.  I will re-set the DIP switches and look for a NF meter!