I did a few more tests today with the 10073C probes and found they are not as bad as I thought - I was falling into the long ground wire trap - still getting used to having a 1GHz scope. I got a small black tip with ground spring accessory and used that to connect to my signal generator, the probe did OK out to 500 MHz where the voltage was falling off but the signal was still good - about ½ voltage (-3dB?) so I will keep a couple at least.
Today the used 1156A arrived, it looks perfect and has every accessory including the little plastic vial of tips but, when I plug it into the MSO7104B, it says "Unsupported probe attached to channel 1". I've done some online research to answer the obvious question - is it really supported?
1. Is the 1156A supported by the MSO7104B?
This links says "These Infiniium active probes are not supported by InfiniiVision Series scopes – 1152A, 1153A, 1154A, 1155A, 1159A, 1168A, 1169A, N2800A, N2801A, N2802A,
N2803A, N2830A, N2831A and N2832A.." which sort of implies it IS supported.
2. On page 54 of the
MSO7000B manual is says that the 1156A is a supported probe.
So it does look like it's supported so I'm thinking of things that could be wrong; one is that the EEPROM has become corrupted and is not responding to the query from the scope. I wonder if there's a way to issue a command from the scope to interrogate the probe? It might just need reflashing.
I went onto the Keysight web page to explore the option of returning it for repair but, as far as I got, it appears that they want $1,569 to repair it which is insane considering the N2795A Active Probe, 1 GHz is $1,056 on their web site for a new one! I will try to call them tomorrow to clear this up.
I've designed an FET probe PCB (see picture) based off the poor man's 1 GHZ probe project - I've ordered 10 PCBs (85 x 14 mm)and some components - I included a place for a 3mm white LED that will shine on the PCB under test. Worst case, my 1156A probe will be dismantled to look into the Autoprobe interface and see if I can make it give me the supply voltages I need.
It would be nice to have a 3D printer to print some cool cases for this probe.
I also have been researching some of the newer Op Amps with the idea of making a differential probe with reasonable offset capabilities like the 1130A which is $4,001