Tektronix S-6 vs S-4, etc. - Page 1
Forum section: electronics / testgear

author: Electro Fan
author_rank: Super Contributor
timestamp: December 22, 2015, 07:37:39 pm
content: Just checking to see if anyone has a preference for one or the other? Seems like the differences are a few ps in rise time and the loop back feature on the S-6 - and also the acceptable voltage (+/- 5V on the 4 and +/- 1V on the 6); not sure how useful the loop back is or if it is enough to offset the larger voltage range. Thoughts?---On a related question, a S-52 is a pulse OUTPUT generator? (Opposite of a S-X sampling head that samples an input signal)?----On other related questions - presumably a S-2, S-4, S-6 will take a fast rise time pulse and sample it within the Sampling Head and with an 7S11 and 7T11 be able to display a trace with a very fast rise time (as fast as 25ps) on a 7000 mainframe even though the mainframe is spec'd at the max to 1 GHz (7104) or even only 500 MHz (like the 7904)? So even though the 7000 series mainframe scopes with their standard plug-ins would normally be limited to 350ps rise time (at 1 GHz) or 700ps rise time (at 500 MHz), with the sampling head they can render much faster rise times? Just making sure I've got this fundamental concept correct. Thanks

author: PA2HK
author_rank: Contributor
timestamp: December 22, 2015, 10:40:38 pm
content: Both the S4 and the S6 offer the same voltage range (5V), the S6 is designed to be used in a TDR measuring setup although it can be used single ended, just put a 50ohm SMA terminator on the other port, a S6 has no internal triggering (triggering is done via a TDR pulse). An S-52 is a pulse generating head, typically used to generate the pulse in a TDR setup that can be used together with a S6 sampling head in a 7S12 plugin, S-52 will also work as a pulse generating head in a 7S11. Given the choice I would go for a S4, sampling head does not need a terminator, has higher specs and offers internal triggering.The 7T11 is sampling at max 50kHz and can only be used to sample highly repetitive signals. IIRC a 7T11 can only trigger up to 500MHz internally, you may need an external delay line like a 7M11 to tee a pre-trigger signal of in sampling high frequency signals or alternatively have the sampling combination run freely without triggering (needs some dial fiddling), a 7M11 works nicely but requires some more steps to setup.A mainframe' max rise time does not affect the max rise time of the sampling system, a 7S11/7T11 combination will work equally well in say a Tek 7603 or in a 7904 (a 7104 is not recommended for sampling systems). Sampling systems from this vintage work best in analog storage mainframes or in the hybrid 7854; these setups allow to retain the sampled view longer. Mind you, these older sampling systems are not easy to use, they are not plug and play systems and apart from the tiny sample memory offered in a 7854 the phosphor in the CRT forms the storage, if the sampling buildup is slow you may never see the sampled signal other then some fading dots on a non-storage mainframe CRT.My preferred sampling setup in the Tek 7000 series is the S4 with 7S11/7T11A in 7854 digital mainframe. I have collected lots of Tektronix stuff in the past and still have 11 7K series mainframes with a nice collection of plugins. Yes, I am utterly madMust say that I do not use these grand machines as often anymore, they are simply no match for modern DSOs; they only get used over here in "the shack" for special measurements (e.g. steep pulse sampling, differential measurements using 7A13/7A22) and for sentimental reasons. Nowadays I would not buy a 7000 series mainframe just for the sampling plugins, there are much better modern/older (read digital) sampling systems that are easier to use and that do offer a digital memory.