Welcome Guest! To enable all features please Login or Register.

Notification

Icon
Error

Options
View
Go to last post Go to first unread
igy137  
#1 Posted : Friday, July 24, 2015 10:44:26 AM(UTC)
igy137

Rank: Member

Groups: Member
Joined: 10/9/2012(UTC)
Posts: 25
Switzerland

Thanks: 1 times
Hi,

I was measuring my power supplies, and found that the trident output powering the XO has a 12.5MHz ripple on it's output (hopefully I read/calc it correctly). As this is 1/8 of the XO freq, I'm wondering it has anything to do with it. Is this normal, or should this be just as clear as the other tridents?

Thanks,
igy

Edited by user Friday, July 24, 2015 10:46:21 AM(UTC)  | Reason: Not specified

igy137 attached the following image(s):
4.png (28kb) downloaded 28 time(s).

You cannot view/download attachments. Try to login or register.
avr300  
#2 Posted : Friday, July 24, 2015 1:50:57 PM(UTC)
avr300

Rank: Member

Groups: Member
Joined: 6/17/2008(UTC)
Posts: 921
Denmark

Thanks: 1 times
Was thanked: 70 time(s) in 69 post(s)
Hi Igy.

When measuring are you using a grounding spring ?

(like this grounding spring)

Edited by user Friday, July 24, 2015 2:13:15 PM(UTC)  | Reason: Not specified

igy137  
#3 Posted : Friday, July 24, 2015 1:59:40 PM(UTC)
igy137

Rank: Member

Groups: Member
Joined: 10/9/2012(UTC)
Posts: 25
Switzerland

Thanks: 1 times
I used the standard tektronix probe of the scope (http://www.tek.com/datasheet/passive-probe/p6139b-%C2%B7-p5050b-0). I used the clip, not the spring. (Clip to the trident gnd, probe tip to triden out pin). I also tested the other tridents, they're clean with the same setup. (Except my avcc, which shows the ~260khz triangle wave noise issue, discussed elsewhere on this forum).

Edited by user Friday, July 24, 2015 2:01:02 PM(UTC)  | Reason: Not specified

avr300  
#4 Posted : Friday, July 24, 2015 2:01:57 PM(UTC)
avr300

Rank: Member

Groups: Member
Joined: 6/17/2008(UTC)
Posts: 921
Denmark

Thanks: 1 times
Was thanked: 70 time(s) in 69 post(s)
Try using the spring to see if it makes any difference.
igy137  
#5 Posted : Friday, July 24, 2015 2:08:54 PM(UTC)
igy137

Rank: Member

Groups: Member
Joined: 10/9/2012(UTC)
Posts: 25
Switzerland

Thanks: 1 times
I'm not sure it'd make a difference; if it's some external noise picked up, I'd expect this to be present in the other tridents' measurements, and none of them showed this.
avr300  
#6 Posted : Friday, July 24, 2015 2:12:42 PM(UTC)
avr300

Rank: Member

Groups: Member
Joined: 6/17/2008(UTC)
Posts: 921
Denmark

Thanks: 1 times
Was thanked: 70 time(s) in 69 post(s)
Sounds logical. You might be right.

My experience is I can't measure anything without the spring. Environment is just too noisy.
Russ White  
#7 Posted : Wednesday, August 26, 2015 9:03:23 PM(UTC)
Russ White

Rank: Administration

Groups: Administration, Customer
Joined: 10/24/2006(UTC)
Posts: 3,978
Location: Nashville, TN

Thanks: 25 times
Was thanked: 89 time(s) in 83 post(s)
Yu also have to watch for loops between the scope and the device under test. AC - transformer coupling can help there.
Rss Feed  Atom Feed
Users browsing this topic
Forum Jump  
You cannot post new topics in this forum.
You cannot reply to topics in this forum.
You cannot delete your posts in this forum.
You cannot edit your posts in this forum.
You cannot create polls in this forum.
You cannot vote in polls in this forum.