Rectify 500MHz Small Signal
in [Design]
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From: Joerg on 5 Oct 2009 16:31 JosephKK wrote: > On Fri, 02 Oct 2009 11:51:54 -0700, Joerg <invalid(a)invalid.invalid> > wrote: > >> Nico Coesel wrote: >>> Joerg <invalid(a)invalid.invalid> wrote: >>> >>>> Nico Coesel wrote: >>>>> Joerg <invalid(a)invalid.invalid> wrote: >>>>> >>>>>> JosephKK wrote: >>>>>>> On Tue, 29 Sep 2009 20:00:49 -0700, John Larkin >>>>>>> <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: >>>>>>> >>>>>>> 20 years away from the lab and i don't remember what is good stuff any >>>>>>> more. The stuff must be functional, but 20+ year old stuff is quite >>>>>>> acceptable. For computer interactivity i expect to buy/use USB to >>>>>>> GPIB converter(s). Serial is acceptable as well. >>>>>>> >>>>>>> My proper email address is in the headers. I have an objection to >>>>>>> dealing with e-prey or preypal myself. >>>>>> Unfortunately EBay has monopolized the market for 2nd hand, they are >>>>>> almost like Walmart. So they call the shots, and thus also the fee levels. >>>>>> >>>>>> The 2465 is a very good choice, this is the scope I always recommend to >>>>>> clients whom I feel are in dire need of a "real" scope. Can't go wrong. >>>>>> But remember that those things can be very tired. >>>>> I bet the Lecroy LH314H (rebranded Iwatsu SS-7847A) is just as good as >>>>> the 2465 and more recent. Sometimes they come quite cheap on Ebay. >>>>> >>>> Got a link? Search engine didn't find it. So far I was less than >>>> impressed with LeCroy scopes but maybe they've got a gem somewhere. The >>>> epitome of ghastliness are Windows-based scopes ... yuck. >>> The is an all analog scope (at least the measurement part) and its not >>> made by Lecroy. Its the first one on this page: >>> >>> http://www.iti.iwatsu.co.jp/en/products/ss/ss_top_e.html >>> >> Ok, but that ain't LeCroy. Thanks for the link though, have bookmarked >> it because there will come a point where I am still recommending Tek >> 2465 scopes to clients but the supply will have shriveled up. They >> (unfortunatly) don't make'em like they used to. > > About us$ 8000 new, probes extra it seems. Nor have i ever heard any > reason to seriously doubt Iwatsu spec's. > 8-) AFAIK Iwatsu has a good reputation. But a Tek 2465 from Ebay would only be around $500, plus possibly a new round of knobs for another $100 or so, plus a couple hours of sweat equity. The delay-trigger shifter on those things is kind of wimpy and its plastic gets brittle. Almost the best analog scopes since sliced bread but on the mechanics they could have done better. -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
From: Archimedes' Lever on 7 Oct 2009 19:51 On Mon, 28 Sep 2009 10:25:05 -0700, John Larkin <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: >On Sat, 26 Sep 2009 17:58:27 -0700, Archimedes' Lever ><OneBigLever(a)InfiniteSeries.Org> wrote: > >>On Sat, 26 Sep 2009 16:52:40 -0700, John Larkin >><jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: >> >>>On Sat, 26 Sep 2009 17:28:50 -0400, "Michael A. Terrell" >>><mike.terrell(a)earthlink.net> wrote: >>> >>>> >>>>John Larkin wrote: >>>>> >>>>> There's the slideback technique: drive a comparator with RF on one >>>>> side, DC feedback on the other. Tease the DC appropriately. >>>>> >>>>> I once made a slideback sampling oscilloscope, using tunnel diodes, as >>>>> my EE senior project. I won an award and had to attend a dreadful IEEE >>>>> chapter banquet and repeat it to a bunch of old-fart power engineers >>>>> who didn't understand a word I said. I described the slideback >>>>> sampling scope in this ng some years back and a certain party loved >>>>> the idea so much he later decided that he'd invented it himself. >>>> >>>> >>>><http://store.americanmicrosemiconductor.com/diodes-tunnel-diodes.html> >>> >>>TDs are insanely expensive nowadays, ballpark $100. I used to get them >>>for a couple bucks from Allied. The fabrication process is insane, and >>>nobody ever modernized it. >>> >>>There are some more modern planar germanium back diodes, essentially >>>low Ip tunnel diodes, but they're RF detectors, useless for switching. >>>Pity, I used to like tunnel diodes. >>> >>>http://aeroflex.com/AMS/Metelics/pdfiles/MBD_Series_Planar_Back_Tunnel_Diodes.pdf >>> >>>John >> >> >> Try PiN diodes then. > >For what? Certainly not switching, amplifying, oscillating, detection, >or mixing. That certainly is what they get used for at 5 to 30 GHz. > >There was a single-TD circuit that was an RF amp, a local oscillator, >a mixer, and an IF amp. One TD and a couple of passives would make an >FM transmitter. > >The beefier td's would make a voltage step with a 22 picosecond rise >time... in 1964. > >John > >
From: Michael A. Terrell on 8 Oct 2009 00:36
MooseFET wrote: > > On Oct 5, 8:32 am, "Michael A. Terrell" <mike.terr...(a)earthlink.net> > wrote: > > John Larkin wrote: > > > > > Too much cheap surplus stuff on ebay, too. I'd love to do a cheapish > > > USB TDR, but there's probably no good market. > > > > Target the CATV and telephone installer markets. Something they can > > use with a laptop should sell > > Ideally, it shouldn't need the laptop to do the check. It should > charge its self from the USB. Idally, you should know something about the application. Using a TDR with logging would make troubkleshooting much eaiser. If you can store all the details of several hundred miles of coax in a self contained, USB charged device the market is waiting. > It should have a "cable active" light on it. > > There is enough POE systems to make a DC voltage measurement a good > idea. There is 60 volt AC modified sinewave on a lot of CATV coax. > It should be defended against mains voltage on the wires. I say this > from sad experience with an RS-232 cable and a chassis that got hot > somehow. Like I said above, you need to know the market. > > What would be nice is a four channel TDR to test ethernet cabling. > > That would show proper wiring pattern and cable condition. Four > > differential outputs to test the twisted pairs, and a 4*2 input mux to > > select each pair in turn. The ability to drive each pair separately > > would allow testing for crosstalk, as well. > > > > The ability to save or print the data on an installation would make it > > a lot easier to troubleshoot, later on. > > > > -- > > You can't have a sense of humor, if you have no sense! -- The movie 'Deliverance' isn't a documentary! |