Hi Eric, Nigel and all,
I just calibrated the scope traces and seem to have got them to an acceptable degree of correctness, well they are showing the same reading as the MM is!
Still having trouble with the BNC connectors none of which are perfect, but I'm beginning to wonder if then leads I bought have slightly smaller pins than perhaps the old ones did, they seem to have a bit of play in them when plugged in, metric plugs and imperial sockets? Is there such a thing in BNCs?
Anyway just going to knock up square wave generator as Eric advised and play with the scope a bit more!
Al
hi Al,
Look at this link 50R versus 75R bnc's
https://en.wikipedia.org/wiki/BNC_connector
Extract:
Specifications
BNC connectors exist in 50 and 75 ohm versions. Originally all were 50 ohm and were used with cables of other impedances, the small mismatch being negligible at lower frequencies. The 75 ohm types can be recognized by the reduced or absent dielectric in the mating ends. The different versions are designed to mate with each other,[1] although the impedance mismatch will lead to signal reflections. Typically, they are specified for use at frequencies up to 4 and 2 GHz, respectively.
NOTE. The physical sizes of the 50 and 75 ohm sockets are slightly different and can damage the "wrong" plugs.
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