| Electronics > Beginners |
| Scope probe to bnc adapter-type panel mount socket. |
| << < (3/4) > >> |
| Greg Robinson:
Ok, guess it more resembles an octopus circuit then? |
| David Hess:
At curve tracer speeds, you do not need to terminate the transmission line between the external curve tracer and oscilloscope inputs. Even up to 20MHz, no termination is required unless the transmission line is long. You might want to check out how Tektronix implemented the vertical outputs on their old oscilloscopes. They use a 950 ohm impedance to drive the 50 ohm transmission line. Into a 1 megohm input, this typically yields 20+ MHz determined by the cable capacitance and into a 50 ohm input, it yields full bandwidth to 100s of MHz with an attenuation of x20. |
| Greg Robinson:
Alright, seems we've got hung up on the 50 ohm termination thing. If you recall, in my first post I actually stated I DIDN'T want to do that. My main question hasn't been touched on at all though. Does anyone know if panel mount scope probe sockets (similar to the common probe-to-BNC adapters but without the intermediate BNC) exist? |
| David Hess:
--- Quote from: Greg Robinson on December 12, 2018, 11:36:33 pm ---Does anyone know if panel mount scope probe sockets (similar to the common probe-to-BNC adapters but without the intermediate BNC) exist? --- End quote --- Printed circuit board versions exist but are expensive; they look like a Peltola socket. Tektronix used panel mount probe tip sockets occasionally for the compensation output but I think they were custom made for them. |
| gcewing:
I think what people are saying is that the sweep rate of your curve tracer doesn't need to be very high, so keep it low enough that transmission line effects in the cable are negligible. Then you don't need to bother with 50 ohm termination or impedance matching or any of that stuff. Just connect it directly to the scope inputs with an ordinary piece of coax. |
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