On Thu, 19 May 2005 20:49:29 -0400, Chuck Harris
wrote:

chuck wrote:
From one Chuck to another,

Thanks for the info and the advice! I will definitely look further into
the '13 and '14.

I do understand the need to sweep "slowly" at narrow RBWs. But I'm still
troubled by the fact that the *slowest* sweep built into the 7L12 is 10
msec/division! That will, arguendo, degrade the filter response. The
storage scope will surely not sweep the SA at a slower rate, and putting
a distorted SA output signal into a storage scope can't possibly reshape
the response! So there is no cure. If our assumptions are correct, this
is a fatal Tek design flaw (not a whole lot of them around).

A storage scope would be really important if the SA is sweeping too
slowly for the regular scope's persistence, or to capture a single-sweep
trace. Or for simply storing a trace for later viewing. But if the sweep
rate is 10 sweeps/second, there shouldn't be much flicker with P31.

Something is amiss here, I think. Maybe there is a typo in Tek's spec
sheet? Or more likely, a parity bit error in my cpu!

Chuck

No, your data sheet is wrong. The slowest automatic sweep is 10 secs per
division. The slowest sweep is manual. This specification exists across
the entire 7L line.


That's not what this says:

http://www.tucker.com/images/images_spec/00000453.pdf


I wouldn't assume that the resolution BW of the 7L12 would be adequate
to look at IMD down 40+ dB at 1 KHz spacing. The BW is specified as
300 Hz at -6dB with a -6 to -60 dB shape factor of 4:1. I don't have
time to plot the selectivity curve at the moment, but it might be an
exercise for you.

If you have a "perfect" cw signal as input, when you sweep it, what
you are plotting on the screen is the filter response of the SA.

Figure a Gaussian response with the specified shape factor and then
overlap two of the curves with 1 KHz spacing and see if the filter
skirts are down 50 dB where they overlap. (You should have 10 dB of
margin IMHO)

Personally I'd use the HP with a storage mainframe.