[Amps] Sampling RF at input and output of an amplifier

[Paul Christensen]

>I want to use an oscilloscope to view the relative timing of the relays in 
>my homebrew QSK system, and would like to be able to sample the RF as 
>simply as possible. Absolute amplitude isn't important, but timing is. What 
>is the minimalist approach?

Pete,

For quick QSK timing measurements, I often inductively couple the sample 
point to the scope.  You can use a short coaxial jumper with BNC connectors 
on both ends and connect one end to the scope, the other end to a 
BNC-to-banana adapter.  Then, take an alligator clip test lead and wrap it 
in close proximity to the sample point.  The lead ends are connected across 
the adapter.

Unless you're sampling low power, there's often enough coaxial leakage to 
just wrap the lead around the coaxial jumper.  Then, adjust the scope's 
vertical amplifier to fill the display.  Generally, I can get good display 
quality without much noise.  You may need to experiment with more or less 
turns around the line.

Paul, W9AC