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Tektronix 7S14 - URGENT!
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JOSE V. GAVILA (EB5AGV/EC5AAU)
Hello!
I am in need of some info about the 7S14 plug-in... is it worth $150 in operating condition?. How does it performs? Please, any information will be welcomed. Thanks! JOSE ---------------------------------------------------------------------- 73 EB5AGV / EC5AAU - JOSE V. GAVILA La Canyada - Valencia (SPAIN) EB5AGV Vintage Radio Site: European Boatanchors List: |
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John Rehwinkel
I am in need of some info about the 7S14 plug-in... is it worth $150I used one of these plugins for a couple of years back in the 1980's. It worked just dandy for me (measuring risetimes of pulsed electron guns), under some fairly demanding conditions. I'd happily pay $150 for one in operating condition. -- John Rehwinkel spam@... |
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Michael Dunn
> I am in need of some info about the 7S14 plug-in... is it worth $150I have one, though I haven't really used it. It seems to work ok, except for a slight "ghost" signal on one trace. Think mine was closer to U$100! If you get a manual too, I will gladly pay a bit for some photocopies. Keep in mind that these samplers typically have more finicky triggering circuits than a normal module. Also, all the buttons on mine are quite sluggish -- almost binding. I'm sure that'll improve with a bit of maintenance... Michael |
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Stan or Patricia Griffiths
My opinion is that a working and calibrated 7S14 that meets all of its
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original specifications should be worth $150. The problem is that almost nobody has the ability to determine if one is really working properly or not. You have to have a very fast rise and clean pulse generator, an amplitude calibrated 50 ohm voltage source, and a fast time mark generator at a very minimum in order to get any idea if it really works correctly. If it does not work correctly, it may be impossible to find the parts you need to fix it. The most vulnerable parts are the sampling diodes and I suspect they are impossible to find, but I have to admit I have not searched for any. I am sure there are other critical, hard to find parts in the 7S14. Does this unit come with a "money-back guarantee" . . . ? Stan w7ni@... JOSE V. GAVILA (EB5AGV/EC5AAU) wrote: Hello! |
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Mark Kahrs
And don't forget those batteries in the sampling diode bias.
I personally think that the S14 is a washout. You can only go to 1 GHz with it and with a 79xx you can already get to 500 MHz. So, why go to sampling for the extra 500 Meg? Why not just go for the gusto and get a 7S11/7T11 pair? As I remind everyone, you get what you pay for (and that includes advice) (Most of the time) Mark. |
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Don Black
Hi,
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I haven't had any experience with sampling CROs but believe the plugins can be damaged with input signals greater than 5 to 10 volts (depending on model). Be careful to limit input signals as they're very difficult to obtain parts or service. Perhaps others have some comments on this. Good Luck, Don Black. Stan or Patricia Griffiths wrote: My opinion is that a working and calibrated 7S14 that meets all of its |
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Stan or Patricia Griffiths
In most sampling instruments I have encountered, signals start distorting when they
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exceed about 2 volts in amplitude. Damage to the sampling diodes occurs around 5 volts and you never want to apply DC to the input of a sampler. There are a couple of exceptions to this . . . Stan w7ni@... Don Black wrote: Hi, |
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Sometimes, time-mark generators are overrated. The advantage of them
is that they make vertical marks for easily matching marks to graticule lines. But if you need faster timing checks, you don't need to be slaved to an older time-mark generator that won't give you fast marks. As long as you have a signal generator and a counter (or built-in counter on the generator), you can get accurate timing references. A generator capable of 1 GHZ will give you 1ns/div "marks". And if you have a 100ps/div timebase, that only means that you'll have a "mark" every 10 divisions. You don't HAVE to have marks every division to calibrate, although it is nice to check out linearity, of course. Many of the Hewlett-Packard microwave generators can go higher yet. I had a Navy chief who thought he knew everything tell me once that I couldn't calibrate oscilloscopes if I didn't have a time-mark generator. Pulease! |
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Stan or Patricia Griffiths
I hate to disagree, but the Navy Chief had a good point. The military, as
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you know, tends to "go by the book". The book in this case is a Tek manual and it specifies timemark generators. But more important than that, standard timing measurements on scope screens are made from the second graticule line to the ninth graticule line, ignoring the first and last 10% of the sweep. How can you do this if you don't have some reference mark at both of those points? A sinewave with one cycle spread over the entire screen won't do it. You could, I suppose, set your generator's frequency with the counter such that one cycle occupies 8 divisions on the scope screen . . . but even then, there is another problem. Where the sinewave crosses the second and ninth graticule lines, it is traversing the screen at a rather severe angle to those graticule lines. This can lead to errors in viewing this measurement that are well beyond the typical 2 or 3 percent specification of the the scope's timing. This does not mean that WE can't make some very useful timing measurements on scopes with counters and generators . . . we can! Most of us don't have to worry about the stringent rules of a military metrology environment like that Navy Chief certainly did. Extremely fast scope sweep speeds is exactly why Tektronix developed the concept of the "slewed edge" found in the CG551AP and later versions of that scope calibrator. I prepared and presented a stand up presentation on the "Tektronix Slewed Edge" at a metrology conference in LA in about 1979 when I was the Tek TM500 Marketing guru in charge or marketing the CG551AP. The slewed edge is an extremely noval idea on how to calibrate extremely fast sweep speeds, even if you don't have the required bandwidth to view sinewaves at those speeds. Stan w7ni@... dhuster@... wrote: Sometimes, time-mark generators are overrated. The advantage of them |
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