Tektronix delayed timebase operation

This short video shows an example of how you would use the delayed timebase on an oscilloscope. This example uses a Tektronix 485 oscilloscope and bursted sinewave signal from a function generator

Category:

Education

Tags:

• Tektronix
• Oscilloscope
• Delayed
• Timebase
• Tutorial
• W2AEW

[w2aew]

@nlimchua Just viewed it - looks like you've got it. This is exactly what I did during the latter portion of the RF Power Sensor video. Perfect.

[nlimchua]

@w2aew Hi Mr. Wolke, I posted a video response. In it, I show how it behaves on the 2465A and what I did to independently mark the rise/fall edges of the WF simultaneously for both CH1 and 2. Thanks for your guidance.

[w2aew]

@nlimchua When you turn on Delta-T, you should see the 2nd highlighted portion on both the Ch1 and Ch2 waveforms. Double-check that the B-trigger is set to "Run after Delay", not "Trig after Delay". With this setting, you should be able to move the 2 delayed segments freely. The delayed sweeps will apply to both channels.

[nlimchua]

@w2aew I've watched you Charc. RF video but not able to do the same on delta T in my 2465A. ch1=gated RF, ch2=square wave. What happens is (ie.) before delta T is turned on, I have my delay hi-lited on the falling edge of the gated RF WF, when delta T is turned on, I expect to see that *other* hi-lite on the rising edge of the same WF but instead it appears on the gate source WF which is on ch2. So, I have a delay hi-lited on each WF (ch1 and ch2). I'm not sure if it's expctd for 2465A

[w2aew]

@nlimchua The position of the delayed sweep (the delay) will be dependent on how you setup the B-Sweep Trigger settings. The 2465 has a Dual delayed timebase that is activated with the delta-T function. When you do this, the Delay sets the first expanded waveform section, and the delta-T sets the 2nd delayed sweep. Check out my video Characterizing an RF Power Detector to see these controls in action.

[nlimchua]

@w2aew Awesome! Tek went thru some tough times years ago but it looks like they're back with nice products. Between HP and Tek, they've always set the standard for everyone else. I noticed that using delta T on my 2465A does not allow me to swipe the other edge of the gated RF WF, it does allow me to use the delta knob for the gate. Is that how it's supposed to be? I'd like to see more real-world basic apps for scopes and func gens for HAM circuits. Thx!

[w2aew]

@nlimchua I'm glad you enjoy my videos. I spent 20-25yrs as a design, applications and test engineer for several different companies. However, about 6 years ago I joined Tektronix as an Field Applications Engineer - and I love it! Please let me know if there's a specific topic that you'd like to see a future video on.

[nlimchua]

@w2aew thanks for the response! That makes sense. Your videos are very clear and concise, I'd love to see more practical applications esp. with the analog scope (I have a 2465A and an old HP54112d). From your response, I take it - you worked at Tektronix before? If so, in what capacity? I admire people like you who share valuable knowledge.

[w2aew]

@nlimchua The CFG280 pre-dates my time at Tek, so I'm not familiar with it. However, my guess would be that the counter is measuring the output, after you've gated it with the 3KHz square wave. Since you've created a signal that is a 400KHz sinewave for "half" the time, and DC for the other "half" the time, the average frequency is 200KHz. The counter is basically counting edges over a given time period to calculate frequency. Thus, 50% duty cycle gives you 50% frequency measurement.

[nlimchua]

Thank you for your very educational videos. I have a tek cfg280 func gen. I preset the 280 to generate sine at 400khz and feed a gated 3khz square wave (from another func gen) to the 280 to basically get a similar signal that you have. However, I notice that the 280's counter readout shows approx. 200khz - can you explain why this is so? thx very much.