Saul,
When the timebase LED is on, the scope does not sweep at 50 ns/div. The sweep is slower and uncalibrated. I count 17.5 cycles of 24 MHz.
1/24e6 = 41.67 ns/cycle
17.5 x 41.67 = 729 ns total sweep time
729 ns / 10 divisions = 72.9 ns/div
Can you now see why the sweep is uncalibrated?
The same applies to the vertical amplifiers.
I just think that the 24 MHZ 1/4 of full scale of a 100 MHZ scope,be so tight...
Does full scale refer to horizontal scale or vertical scale? My interpretation is horizontal since the 10X magnifier is needed to see the individual cycles of 24 MHz.
To display 80 MHz across 10 divisions:
1/80e6 = 12.5e-9 = 12.5 ns per cycle
50 ns per division = 500 ns per sweep
500 ns per sweep / 12.5 ns per cycle = 40 cycles across 10 divisions
To clearly see the individual cycles requires faster sweep.
An important detail to consider: the stated bandwidth of a scope is that of the
vertical deflection system. The
horizontal deflection is less. For the HP1740A the horizontal deflection bandwidth is 5 MHz. At 50 ns/div x 10 divisions, the effective frequency is only 2 MHz.
RF+ Tech