Tektronix Technical Forums are maintained by community involvement. Feel free to post questions or respond to questions by other members. Should you require a time-sensitive answer, please contact your local Tektronix support center here.

Testing Caps with Tektronix 465

Post Reply
DH1966
Posts: 3
Joined: October 9th, 2021, 11:34 am
Country: United States

Testing Caps with Tektronix 465

Post by DH1966 » October 9th, 2021, 11:36 am

I'm building a tube amp and purchased a Tektronix 465 solely for the purpose of testing capacitors for outside foil end. Can anyone point me to a good tutorial for this task? While I might want to plumb the depths of what an oscilloscope can do with future projects, right now I only need to learn this one set of functions, and I don't have hours to commit to multi-part tutorials on EEVblog or Uncle Doug et al. Your help is appreciated.

w2aew
Tektronix Applications
Tektronix Applications
Posts: 180
Joined: December 2nd, 2008, 2:27 pm
Country: United States
Contact:

Re: Testing Caps with Tektronix 465

Post by w2aew » October 9th, 2021, 11:46 am

Check out the YouTube channel called Mr. Carlson’s Lab. He has a video on the topic.

DH1966
Posts: 3
Joined: October 9th, 2021, 11:34 am
Country: United States

Re: Testing Caps with Tektronix 465

Post by DH1966 » October 9th, 2021, 12:17 pm

Thanks for the quick reply. I checked it out. The problem I'm having is that maybe I need a guide on the 465 more than I do the testing method. I've set my divisions as low as I can, which is a question unto itself, because when I crank the dial all the way over, the indicator backlight is behind 50mV, which is the fourth lowest setting (5mV being the lowest). So, I don't know if I'm measuring at 5mV because I'm cranked all the way down or if I'm measuring at 50mV because that's the one that's lit up. That's not the biggest problem, though. I don't have a wave, I have a line, which I could still deal with, because the line jumps when I hook up the probe leads and grip the cap between my fingers. However, it doesn't hold steady like it does on the videos I've watched, including Carlson's. Rather, it jumps (or dips) and then returns to level. This makes some sense, given how capacitors work, but not only does this not look the same as in videos I've watched, leaving me to doubt the method, but I also can't tell a difference in the amount it jumps before returning to 0 whichever ends the leads are hooked up to. The - below shows my settings. Any corrections would be helpful.
IMG-0094.jpg
IMG-0094.jpg (431.28 KiB) Viewed 260 times

w2aew
Tektronix Applications
Tektronix Applications
Posts: 180
Joined: December 2nd, 2008, 2:27 pm
Country: United States
Contact:

Re: Testing Caps with Tektronix 465

Post by w2aew » October 9th, 2021, 6:15 pm

OK, a few things here...

The reason that the minimum VOLTS/DIV setting you can get is 50mV is because you are using a 10x probe. The 10x probe attenuates (reduces) the signal it is probing by a factor of 10. Thus, the vertical VOLTS/DIV setting is multiplied by 10 - hence the name - 10x probe. The scope senses this 10x probe by the little "pin" along the collar of the BNC connector. If you simply remove the probe from the scope, you'll see the illumination jump from the 50mV to the 5mV setting. Since you are measuring very low frequencies, you can use a 1x probe, or simply a coax cable that has clips at one end, instead of the 10x probe.

On your Horizontal Display pushbuttons, you currently have the "A INTENsified" setting selected. For most basic measurements, you'll want to use the top button selection "A".

When you touch the probe tip, you will often - stray energy from the air, coming from your mains (line) voltage - which will have a frequency of 60Hz (in the US). Your current setting of 2ms/DIV should show you a little more than one cycle of this. The reason that it is not stable is because of your trigger setting. You have selected AC coupling (that'll work) and CH1 as the source, but the "A TRIGGER LEVEL" appears to be dialed way over to the right. Try centering that.

I have *many* oscilloscope tutorial videos on my youtube channel as well. Here's my playlist of just scope type tutorials:
https://www.youtube.com/playlist?list=P ... 8BC2E068E0

DH1966
Posts: 3
Joined: October 9th, 2021, 11:34 am
Country: United States

Re: Testing Caps with Tektronix 465

Post by DH1966 » October 12th, 2021, 7:12 am

Thanks for the feedback! I was out of town this weekend and just got back to this. I will take a look at those settings, - up a 1x probe, and have a look at that youtube playlist (and then probably be back with more questions). I appreciate the help!

Post Reply

Return to “General Discussion”

Who is online

Users browsing this forum: No registered users and 1 guest