[Test-Equipment] Using an HP 331A Distortion Meter

[KA4INM radio]

   On 09/02/14 16:07, Barry N4BUQ wrote:

> I'm a bit new to using a distortion meter and have a basic question.  When connecting the device I want to test to the meter's input, I assume it is necessary to terminate the generator properly (e.g. into a 600-ohm resistor, etc.) and that's so that the generator sees the proper load.

> What's confusing me a bit about this I may use this to measure distortion for a 600-ohm-terminated signal as well as connecting it to the 8-ohm load for the PA output.

> Does the meter not really care what impedance it sees on the input?  It just seems odd that I would feed it a 600-ohm load in one case and an 8-ohm load in another.

> Sorry if the question doesn't make a whole lot of sense but I'm confused a bit as to whether additional matching is necessary to get an accurate reading (or, at least, as accurate as an older analog device like this can give me).

   The distortion analyzer is a Volt meter with a tunable notch filter 
that can be switched into it's input, after calibration.

   The impedance doesn't mater that much when you are measuring the 
amount non-original tone frequency.  (Voltage)
-- 
   Ron  KA4INM - Youvan's corollary:
                 Every action results in unwanted side effects.