> The problem with most of the cheaper spectrum analyzers is
> that they don't
> have enough resolution. For IM measurements you need a 200
> or 300 HZ
> bandwidth filter and enough stability to sweep only a few
> khz of the
> spectrum at a time. Even some of the moderately priced
> units will not do
> that. The old HP141 will do it but even it has stability
> trouble with the
> 1.2 ghz rf head in it. You really need the 110 mhz rf
> front end in it so it
> is stable enough for the narrow sweeps needed to look at
> close spaced tones
> used for IM measurements.
I was going to suggest the very same thing. I can verify
what Gary says.
If you get an old analyzer be very careful. Even the better
of the old analyzers, like the HP141, requires a narrow
frequency range RF section to be useful.
There are a lot of analyzers out there that won't read IM
products well. The dynamic range of the HP141 is about 50dB
before it falls apart, so it is a marginal instrument even
for TA measurements of harmonics.
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