Re: 2235 with 360 kHz 100mV P-P ringing on +100V PSU rail

tom jobe <tomjobe@...>

Hi Goran,
You make some excellent points!
This ripple trash getting into the CRT leads might all just cancel out,
which would completely cancel out my latest thoughts to.
The +100 volt supply is also connected closely to other CRT inputs such as
the Geometry and the Grid Bias, and I do not think they have any common mode
tom jobe...

----- Original Message -----
From: "G�ran Krusell" <>
To: <>
Sent: Monday, May 23, 2011 3:43 PM
Subject: Re: [TekScopes] Re: 2235 with 360 kHz 100mV P-P ringing on +100V
PSU rail

Hello guys,

I think Jerry is right. A 100mV ripple on +100V DC is not the problem in
this case. In some cases the ripple enters as a common mode signal and this
is never a problem. Of course, if you want to do the experiment and insert
an LCL-filter you can do that. Such a filter calls for some calculations but
first you need to measure the DC current. It is quite possible to build such
a filter using some standard components. But my guess is that you will not
see any difference at all.

If you have a substantial rippel on a supply voltage (like 10%) then it
would show up as a problem but this is not the case here. The problem is
somewhere in the amplifier chain I believe...

On the other hand, what tells you that this ripple has the same frequency as
the ripple/noise that you see on the CRT...?


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