[Amps] RF probe and SSB (may be a little OT)

[Peter Chadwick]

Bob said:
>I have a Tek-475, just no probes or manual. The manual I can get from 
the internet, but the plethora of knobs and buttons on the 475 has 
humbled me. To be honest, I have no idea what most of them do.

I know I need a RF probe, but not sure if that is something easy to 
build or buy.<

Get a manual, and read it. You'll learn quite a lot. Buy a pair of standard oscilloscope probes - ones good for 100MHz or so. Probably set you back $50 - $100, but they're a real good investment to go with the very good 'scope that you have. Probes give an attenuation, usually of 10, although there 100:1 probes out there. You can get quite good ones which are switchable to be either a times 1 or a times 10. In times 10, they provide much less loading of the circuit - usually, they are something like 10 Megohm in parallel with about 10pF. If I remember correctly, the Tek probes for the 475   automatically switch the indicator lights on the scope so that it always reads right, so if you can get the proper Tek probes, it's worth it. You also need to adjust the probe, but that's doen by connecting it to the calibrator output on the scope and adjusting the internal capacitor until the waveform is nice and square. Not a major task.
For really low loading, you need a FET probe, but it won't be necessary for what you're trying to do. Mine cost me $120 at Dayton the other year:  I don't often use it, but when I do need to, it more than earns its keep.
You might find an 'introduction to oscilloscopes' book somewhere, but I couldn't say where - maybe one of the introductory electronics books might be the thing. The only one I've got is a pre WW2 one, and that is of historical interest only - they didn't have scope probes, triggered timebases, delayed timebases or bandwidths over about 2MHz in those days! It even goes into gas focussed CRT's.....
73
Peter G3RZP