Products > Test Equipment
Help needed - Siglent TPA10 / Tektronix TekProbe offset not working
<< < (5/6) > >>
FlexibleMammoth:
I made some calls to professors and lab engineers at our university. Unfortunately, across two campuses I found no one that still has a scope with a tekprobe interface - the only old scopes they had were before tekprobe.

For the moment, I do not have access to a native tekprobe device. I will report back once I find one, maybe they let me borrow it.
FlexibleMammoth:

--- Quote from: TimFox on February 09, 2022, 09:15:46 pm ---I have a Tektronix power supply/adapter for TekProbe.  The "offset" pot does not function with some of the Tektronix TekProbe probes.

--- End quote ---

Tim - which adapter do you have? A TPA-BNC , the 1103 standalone unit or something else?
TimFox:
I have a Tektronix 1103 power supply/adapter and a Tektronix P6243 probe.
The 1103 does have an offset pot on each of the two channels, but I believe the P6243 does not use that analog voltage.
FlexibleMammoth:

--- Quote from: TimFox on February 13, 2022, 10:54:23 pm ---I have a Tektronix 1103 power supply/adapter and a Tektronix P6243 probe.
The 1103 does have an offset pot on each of the two channels, but I believe the P6243 does not use that analog voltage.

--- End quote ---

That is interesting - could it be that Siglent *did* implement the 1103 specs? Maybe a genuine 1103 psu only provides offset on pin 5, and the scope provides its internal offset as usual. The result is that you can adjust some probes at the 1103 and some at the scope.

If Siglent copied that Design, there is a problem: as the TPA10 shares an offset control with the scope, that knob will control  both the traditional frontend-style offset and pin5. Now if a probe supports both, then you end up with 2x the offset you select.

So maybe when the TPA10 is detected, they disable the frontend offset - not realising that there is a number of tekprobe probes that do not use the tekprobe-Style offset on pin 5 but rely on the scope.

In a real tekprobe scope there must be some way of addressing that problem… Or I am completely off the mark here.

(Of course there is a German word for the feeling of being wrong about something: „Ich bin auf dem Holzweg“ - literal translation „I am on the wood way“ :beer: )
FlexibleMammoth:
While cleaning up my hard drive, I found that the Tek probe selection guide specifies what is TekProbe Level 1 and 2 (page 2).

My initial suspicioun was right - TekProbe Level 1 is just the metal ring around the BNC for detecting the attenuation factor.

So the 1103, and all active TekProbe probes, are TekProbe level 2.

Also:
- "Some probes require an external power supply (1103) when used with the TDS3000 series." (p.2)
- The P6243 offset is listed as N/A. (p.5)
- The ADA400A offset is listed as "±1 to ±40 V**" with the stars meaning "Based on Gain Setting" (p.9)
- The P6247 offset is listed as "depends on scope". (p.9)



--- Quote from: TimFox on February 13, 2022, 10:54:23 pm ---I have a Tektronix 1103 power supply/adapter and a Tektronix P6243 probe.
The 1103 does have an offset pot on each of the two channels, but I believe the P6243 does not use that analog voltage.

--- End quote ---
That would explain this problem, too: P6243 does not support offset.


--- Quote from: alm on February 09, 2022, 09:18:17 pm ---I have a Tek TDS3052, which may not support the TekProbe offset feature. From what I remember reading in catalogues, the P6243 single-ended FET probe, which does not have the offset feature, is recommended for the TDS3000 series, while the P6245 probe, which does support offset feature, is recommended for the TDS600/700 etc. I measured pin 5 as indicated by the attached diagram without a probe connected, and it stayed at 0V regardless of the setting of the offset control. The offset control also works with simple passive probes. Note that this offset feature is separate from the vertical position control. The way the manual describes it, it can prevent the scope from clipping a signal that's out of range, so clearly the offset is applied in the analog input circuit. As far as I know, it controls the offset voltage fed into the vertical amplifier. It might be that when it detects an active probe with offset feature, it supplies a voltage on pin 5 instead, but it's quite hard to measure while a probe is attached, since the case covers the area around the connector.

--- End quote ---
This is also consistent with the information in the probe selection guide.
Navigation
Message Index
Next page
Previous page
There was an error while thanking
Thanking...

Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod