Re: My 2465B has arrived + A5 Board leaky caps cleanup
Noise is endemic in electronics. It is related to thetoggle quoted messageShow quoted text
temperature. The resistors, transistors, etc.. All make
a contribution to the noise.
The noise of a receiver is set by the noise of the front
end of the receiver. Once established, any further
amplification simply amplifies the noise... the signal to
noise ratio stays basically the same.... well, until overload.
When you have the scope in the higher gain positions, the
noise is being amplified, and is displayed as more fuzz.
Noise of this sort is called white noise. Its distribution
is fairly uniform across the frequency band of the scope.
If you run the scope at its full 350MHz bandwidth, it is
slurping in all of the front end's noise from DC to 350MHz,
and adding it to the trace, everywhere...
If you reduce the bandwidth of the scope, to say: 20MHz, there
is less overall noise to add into the trace, because there is
less overall bandwidth... the noise from 20MHz through 350MHz is
About the blink: Sorry, it has always been there with the
2465A and B models. It is not as apparent with the plain
model, mostly because the LED's are dimmer.
Wnen the LED's registers are loaded with the state of the
LED's on the panel, they all go into an LED ON state for
the duration of the load. It is a feature of the register
CAL 05 is the routine that can read/set/reset the counters.
Its default position is to reset the counters. You can
set them to whatever you want... the technique requires
you to select the increment using the X10 button, and to
rotate the Delta Ref, and the Delta controls to make the
appropriate counter change... I know of nobody that does
There is no specific manual for this option, but rather
there is the main instrument manual, and the GPIB options
GPIB on the 2465B is a complete waste for the usual user.
It only allows you to set the front panel controls, and
display some text on the screen. It does *not* allow you
to read anything that is derived from the CH1-4 inputs.
It's purpose is for use with the rack panel version of the
scope, when using the scope to do mindless calibration
and repair routines of military equipment. Basically, it
replaces the calibration manual with a computer as the
source of calibration information.
Chuck as usual your explanations are outstanding. After reading them, just a few short extra questions/comments, bellow.