General > General Technical Chat
The Rigol DS1052E
DavidDLC:
I haven't read the hole topic, but I just found this out !!!
http://hackaday.com/2010/03/10/50mhz-to-100mhz-scope-conversion/#comments
DavidDLC:
Whaaattttt never mind, the took it from here.
Sorry.
loydb:
Another newbie stumbling here from Hack-a-day. I'm in the market for my first scope, this is fascinating reading.
JimBeam:
Hello everybody.
I am new to the forum - but I think I have to correct a few things here... :-[
The circuit between pins 8 and 9 and the ADC amp indeed limits the bandwidth to about 20MHz - when you activate the "BW limit" from the channel menu!
When you take a close look on the part in the middle (D1), you see a small grey bar on the right hand side - as this is neither a cap nor a coil, but a diode, supposedly a varactor diode! And the parts at the upper and lower end of the "filter" are no caps either, they are simple resistors (R1 and R2). R1 goes to ground, R2 is HF-shunted to ground via C3. The control signal comes from somewhere via R3 and biases the diode.
The series circuit of C1, C2 and D1 is a small condenser in the range of well below 1pF to some pF - depending on the control voltage and thus the capacitance of D1.
When you remove C1 you do not only remove this serial capacitance that limits the bandwidth in any case (at any value of the control voltage) - but you also disable the BW Limit function from the menu altogether!
Btw., when you look at the real circuit, it now is obvious, that after removing C1 a removal of C2 doesn't change anything more...
Andreas
Simon:
so are you saying that if the variac diode is shorted all filtered limits are removed so the scope will be open to all frequencies ?
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