Re: Function Generator Output Impedance

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "davep by way of Terry Fritz <twftesla-at-qwest-dot-net>" <davep-at-quik-dot-com>


> All nice signal generators are based on 50 ohms output impedance.

	Some are, some aren't.  AND presence of a 50 ohm connector
	(BNC, et al) or a label '50 ohms' can be, Wellllllll
	'tricky'.

	Before trusting a generator to be 50 ohms (or any other value)
	its easy enough to rough check:

		Measure the output voltage.
		Load with 50 ohms, measure again.

	If the second is half the first, then the generator is
	50 ohms (roughly).  If the  second is something else, do
	the math.  AND, for rigorous work,  its a good idea to
	check the apparent impedance at several freqs of interest
	and at a couple of output level settings.  Just in case..
 
> This protects the generator and allows the use of 50 ohm coax and 50
> ohm loads to keep signal integrity.  Not good for running "real power"
>however.  

	???

	I've seen 50 ohm (specialized) used up to megawatts...

	best
	dwp