Yeah but the scope is 50R terminated so I didn't think that putting 1Meg in // with the counter, would make that much of a difference.. 1Meg // with 50R is still pretty much 50R ![Confused :-//](https://www.eevblog.com/forum/Smileys/default/confused0024.gif)
Played with rise times. That did it, was interesting.
Since the beginning the pusle generator was set to its fastest rise time, 5ns.
So what I did was increase the puls width until the 1Meg input would regsiter. It happened with a pulse width of 27ns.
Then I backed off a little, 26ns, so the counter would not register anymore.
Then I started increasing the rise time (and fall time equally) to see how / if it would have an impact on the shape of the waveform, and it the counter would behave any differently.
That was success.
I increased rise time very progressively, in 0.1ns increments. At 7.2ns the counter started flickering, was picking up some pulse.. and at 7.4ns, it was able to read reliably, was stable.
The shape of the signal however is barely changed to thje naked eye.. but clearly the counter does see the difference !
It was like clock work : redude pulse width by one ns : doesn't count anymore. Increase by 1ns.. hey presto works again. Same with rise time. 7.4ns works solidly, 7.2 it's unstable, 7.0ns no counting at all.
It's fun being to control pulse width and rise times, accurately, and see how the counter reacts while looking at the waveform on the scope ![Cool 8)](https://www.eevblog.com/forum/Smileys/default/cool.gif)
Yes, but every cable is a transmission line. The question is: where is the T-piece? If you have the T-piece on generator or scope, the cable between generator and scope is terminated (by scope) but the other end is "flapping in the breeze". If that is the case, put the T-Piece on the counter: Now the whole line from generator with the counter in the middle is terminated by the scope on the other end.
Ah thanks yes I was starting to wonder about that... beginner here... I am in a new territory here... now that I have fancy cables and adapters, I am leaving the "cobble any piece of wire and banana together until you can display "some" signal... to " you have got all the proper cables and adapters now, so it's about to get the PROPER signal, rather than just "some" signal " !
![Grin ;D](https://www.eevblog.com/forum/Smileys/default/grin.gif)
As can bee seen in my pics, I put a ' Y ' splitter at the generator output. One coax cable going to the scope, 50R termination because it offers that possibility, and another cable from the generator to the counter 1Meg input. OK so I need to add a 50R termination at the counter to see if that improves things, which it probably will !
![Embarrassed :-[](https://www.eevblog.com/forum/Smileys/default/embarrassed.gif)
I have a bucket load of 75R termination but not a single 50R one ! Oh boy how come I didn't think of adding that to my Farnell order the other day when I ordered all the cables and adapters !
![Banging Head |O](https://www.eevblog.com/forum/Smileys/default/bangheadonwall.gif)
Will add that to my cart list for my next order... in the meantime I can maybe just cobble a hand home made termination with a 50ohms discrete resistor, which won't be perfectly 50ohmsd I guess, bvut close enough to see an improvement. Or a little trimmer to make it perfectly 50ohms... Yeah I will play with that see what that does
![Cool 8)](https://www.eevblog.com/forum/Smileys/default/cool.gif)