EEVblog Electronics Community Forum
Products => Test Equipment => Topic started by: Gianni on September 05, 2022, 08:23:03 am
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Hello,
I own 3 7A18 plug-ins and I tried for the first time to calibrate one channel of on of them. I am a little confused, so I ask for some help.
- The calibration appears almost correct for both 1x (5mV) and 100x (0.5V) attenuator positions
- In x4 20mV and x10 (50mV) I have a "curl" (see photos) that I am not able to eliminate
- The "flat top" control seems to have no effect, not only here, but also on the correctly working channel and everywhere I checked it
- I already tried to replace C114/C115 but without any change
I would be grate to whom could help me.
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Your unit isn't that bad. I've certainly seen worse with Tektronix 7000-series vertical plug-ins. They are without a doubt very difficult to calibrate properly.
I assume you have switched the x4 and x10 attenuators across channels. This might tell you whether it is an attenuator problem or something else.
In general, all these Tektronix cam mechanisms often benefit from a thorough cleaning. It's best to pull the entire attenuator board out, remove the attenuator blocks, and go at it with alcohol. Saturate a thin strip of paper and work it beneath the leaf contacts on the board while gently pressing down. Be very careful. Let the alcohol thoroughly dry for a few hours - nothing will work correctly if the board is still wet.