Re: Tektronix R7844 Problem: can not set intensity and focus


 

Don't forget that these diodes need to have fast Trr times because they run at 10's of kHz switching speeds.
 
Tom
 

----- Original Message -----
From: Tom Jobe
Sent: Saturday, May 18, 2013 11:16 AM
Subject: Re: [TekScopes] Re: Tektronix R7844 Problem: can not set intensity and focus

 

Just for a reference point.
A small 12 kV diode I just tested has a forward voltage drop of 25 volts at 5 mA, and it has a 35 volt forward drop at 10 mA.
The data sheet for 2CL73, 12 kV diode rates it at a 37.5 volt drop at 10 mA
tom jobe...
 
 
 
----- Original Message -----
Sent: Saturday, May 18, 2013 7:58 AM
Subject: [TekScopes] Re: Tektronix R7844 Problem: can not set intensity and focus

 

Hello:

If this 12kV diode is made up of 30 diodes in series, each with 0.6V forward bias voltage, then it will start to conduct at 18V, right?

Simple DMM test would not yield meaningful result because the supply voltage is too low to make them conduct, that explains! Thank you.

Y.-J. Wu

--- In TekScopes@..., Göran Krusell wrote:
>
> Hi, 12kV diodes are made up by a number of series diodes and therefore your test has failed. Your diodes may
> very well be ok.
> Göran
>

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