What is causing the strange signal on my PMT R928?

[VolBog]

Good day.
Resently, I bought the Hamamatsu R928.
But when I connect to power suply and connect output to the osciloscope I have strange signal.
Maybe someone know the origin of this signal?

 

[berkeman]

Is it covered or open? What kind of fixture are you plugging it into? Can you post your schematic?

https://www.hamamatsu.com/blobs/1328784013964?blobheadername1=content-disposition&blobheadervalue1=inline%3Bfilename%3D1328467311959.jpg&ssbinary=true

 

[VolBog]

It is open (if you about black cover which usually add to reduce noise).
I use standart D type socket assembly E717-63. And connect to osciloscope directly (the input impedance 1MOhm).

 

[jim hardy]

What are vertical scale and timebase on that 'scope trace ?

In other words - what do we know about your "noise" ?

120 hz would likely be nearby fluorescent lights.

 

[Rive]

So far it looks like common EMI from an SMPS nearby.

 

[VolBog]

Vertical 5mV/division Horisontal 20ns/division
Its look strange in my opinion.
Usually people have like:

But in my case in this pmt I can't see any signal.
Maybe I have broken pmt?

 

[jim hardy]

what does yours look like at those people's settings?

\

shine a flashlight on it through a fan blade.
or point your TV remote control at it and press a button.
tv remote is typically just a bit longer than 900 nm so the tube will probably see it.
.
oops make that might see it.

..