If a decent spectrum analyzer costs $12K, and it may last for 10
> years, that's 1200 a year. Less tax depreciation (or just expense it)
> that's maybe $800, under $70 a month. That's not even coffee+pastry
> money around here. It usually makes sense to buy good new test gear
> and spend your time designing products.
Says the guy with 10 identical old scopes he bought off ebay :)
Sometimes I am thinking about buying half a dozen Tek 2465. Just in case they become extinct on EBay and I encounter another client that has no decent analog scope.
In that case, the older gear is just about as good as the new stuff, at about 1% of the price. Besides, I like scopes!
John
Yeah, me too. (I have a couple of older Tek analog scopes, which I bought *after* the more modern TDS3054).
Anyone used a higher-end modern digital scope?
I have, at a client. Let's put it that way: I was not too enthused. There are many things you just can't do with a digital scope, no matter how many bells, whistle and persistence features they add in.
At the end of the day my recommendation to clients whose labs are exclusively TDS and DPO usually is: Go on EBay and bid on a Tektronix 2465.
I have a 20 Gs/s Tek (7 GHz BW) that I use occasionally...but those sorts of things just aren't as trustworthy as slower ones. They have to sweep a lot of stuff under a huge DSP rug in order to make a nice display. Of course the Agilent ones are smoother looking, but that makes me more suspicious rather than less. One of these times I'll try it out with my 11801C and see if it's telling the truth.
Cheers,
Phil Hobbs
DPO is a real PITA. You *cant* turn it off, but have to go to the correct menu and press the "clear persistence" button to see a single trace. Grrr....
the really annoying thing is that Tek *could* have added a "no DPO" setting, but chose not to.
Cheers Terry
Actually one of the things I dislike about my TDS3054 is that it does
*not* do this much. The trace can be a bit noisy. I see no reason not to have an option to do averaging of its 5Gs/s sample rate, at the lower sweep speeds.
That's usually called 'high resolution' mode, and all my digital Teks have it. Yours doesn't? Weird.
(Of course I hate that mode like poison myself--I try to sit in min-max mode, so I can see what's really being digitized.)
For the stuff I do, I'd be much happier with my 11801C, if only my YAG laser's rep rate were more than 20 Hz--which takes *forever* to get a decent trace, especially since its pulse-to-pulse energy varies almost
2:1 p-p.Cheers,
Phil Hobbs
Cheers,
Phil Hobbs
What do you mean by 'averaging of its sample rate'? You DO have the option of averaging successive traces (Acquisition Mode menu). Perhaps you're referring to some kind of sampling dither? You can also reduce vertical BW to reduce the noise (a little). Paul Mathews
It could, at lower sweep rates, sample fast and average clusters of samples withing one sweep, to reduce noise and improve resolution. Seems to me that something could be done to reduce aliasing, too.
Yesterday I was surprised to see a reverse ringing oscillation. It started as a little wiggle and increased in amplitide, then abruptly died.
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which was of course a flipped-in-time alias of a real, very high frequency ring.
John
I'm pretty sure it doesn't. You *can* average successive traces. This is great for extracting a synchronous signal from noise, like residual switching spikes from a SMPS.
I think it would be very useful for low level analog work in the DC - few MHz regime. Also useful would be a more variable bandwidth, which could also be done with some simple DSP.
[...]
Yes, I was looking for precisely that.
:)
I just hope they haven't replaced all of their old-timers with fresh grads without any field experience. IMHO a scope designer should have
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