Help setting 10x for probe on Tek DPO7104A - Page 1
Forum section: electronics / testgear

author: robertbaruch
author_rank: Regular Contributor
timestamp: April 26, 2018, 02:37:34 am
content: I must be missing something. On my old oscilloscopes there was a manual setting for when you had a 1x or 10x probe. Now, I have one switchable 1x/10x probe, and one 10x probe.However, the 7104 seems to be stuck in 1x mode because when I use the 10x probe, or the switchable probe in 10x mode, all voltages are 1/10 what they should be. So somewhere I would have to tell the 7104 that I've got a 10x probe, no?Can't find the setting anywhere.The closest I've gotten is in the Vertical menu, Probe controls/Setup, and the Type says 1X but it's greyed out, and I can't select it.I tried a probe calibration, but apparently it needs to know the probe type first, because calibrating a 1x probe works fine, but calibrating a 10x probe says it detected no signal -- probably because it's been reduced by 1/10.Where the flaffing setting?!

author: RomDump
author_rank: Regular Contributor
timestamp: April 26, 2018, 03:15:15 am
content: Can you show a picture of the probe? Does it have the tektronix readout pin on the BNC end?

author: robertbaruch
author_rank: Regular Contributor
timestamp: April 26, 2018, 04:27:12 am
content: No, it doesn't. None of my probes are Tektronix. Is that really the only way to get it to recognize what kind of probe it is? No wonder Tektronix went under

author: robertbaruch
author_rank: Regular Contributor
timestamp: April 26, 2018, 04:39:37 am
content: Oh wait, they're still around? I regularly passed the Tektronix buildings in the Bay Area along the 101, and when I saw them being demolished I thought that was it!

author: GerryBags
author_rank: Frequent Contributor
timestamp: April 26, 2018, 04:58:34 am
content: Can't you change the external attenuation in the last panel to 10? Then change it back with the unity 1:1 button when you want to use the 1X?

author: RomDump
author_rank: Regular Contributor
timestamp: April 26, 2018, 10:24:46 am
content: Quote from: robertbaruch on April 26, 2018, 04:27:12 amUsually with all higher end scopes regardless of brand they want you to use their accessories. Tektronix passive probes for this oscilloscope is 1M Input and 500mhz bandwidth limited, ( P6139x TekProbe™ Level 1). For higher probe bandwidth you got to use TekVPI interface.I did go through these manualsUser Manual,Best Practices,training bookand didn't see a manual way to change the the probe attenuation in the instrument, (you may want to go through these to get familiar with the instrument).Be careful plugging probes in and measuring random voltages. You may blow the oscilloscope front end, (have a look at the input specs).I may be mistaken but you can always ask Tektronix directly by calling or opening an e-mail support question case, (you have to register though). It would be neat to know the official answer.

author: nctnico
author_rank: Super Contributor
timestamp: April 26, 2018, 09:50:41 pm
content: I see an adjustable external attenuation field.

author: RomDump
author_rank: Regular Contributor
timestamp: April 26, 2018, 11:47:27 pm
content: Quote from: nctnico on April 26, 2018, 09:50:41 pmI think you and GerryBags are correct. This is what I found in the manual. Attenuation control sets input/output ratio of any external attenuation or gain between the signal and input channels.So setting it to 10 would probably compensate for the 10x probe.Let see what is Robert's results.

author: robertbaruch
author_rank: Regular Contributor
timestamp: April 28, 2018, 12:10:45 am
content: Yes, setting the attenuation to 10 worked! I found that it still wouldn't let me do the probe auto calibration, since that apparently requires attenuation to be 1:1. In any case, I got myself a genuine Tektronix 500 MHz probe, which made me a bit mad because of the cost, but now no fiddling with buttons.Thanks!