DC to 1GHz Probe Construction Plans

[insight]

Has anyone tried this:

DC to 1GHz Probe Construction Plans

cheers, dejan

 

[ronsimpson]

I made something like this that worked well on a 500mhz scope where 10:1 probes did not work.
In this project you are to make a 50ohm terminator. I just bought one.

 

[RadioRon]

I've built several versions of something similar, but a bit cruder and have used them up to 2 GHz for crude measurments with good results. The basic principle of this is sound, and the construction method looks OK. The ones that I've built before used 0402 sized components soldered to the end of a piece of coax and then were glued into a pen barrel along with a gold plated tip pulled from a BNC connector. Same basic idea, but I built both with and without the 50ohm termination and both functioned. In principle, the 50 ohm resistance is a better idea as it provides a correct termination for any reflections coming back from the instrument.

In using such a thing, it is important to realize that this is effectively a voltage probe. So, if you are using it with a spectrum analyzer that displays power, not voltage, you have to translate in your head using the known or guessed impedance at the point you are probing (Alternatively, some analyzers allow you to display voltage directly). If probing a circuit node that you know is 50 ohms, then this is easy, but if you can't estimate the node impedance of the point you are probing, then your guess about the accuracy of the displayed level will have greater error.

 

[insight]

Guys, thanks for the reply.

What is terminator?

regards,
dejan

 

[Nigel Goodwin]

Guys, thanks for the reply.

What is terminator?

It's a humanoid robot from the future in a series of films

 

[JimB]

What is terminator?

A big guy from the future who has come back in time to kill someone.

Seriously, transmission lines such as coax cables etc have a characteristic impedance, if the end of a long cable does not have a resistor across it whose value is equal to the characteristic impedance of the cable, there will be reflections from the end of the cable.

The resistor on the end of the cable is called the terminating resistor, or just terminator.

JimB

 

[Boncuk]

What is terminator?

I know who is terminator. He is now governator of California.

 

[audioguru]

Is a "governator" something like a dictator? A King?

 

[Papabravo]

Is a "governator" something like a dictator? A King?

Those were the fly-ball kind on steam engines.

AND

I believe that a diode is a poem about death.