Rectify 500MHz Small Signal
in [Design]
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From: Nico Coesel on 1 Oct 2009 11:47 Joerg <invalid(a)invalid.invalid> wrote: >Nico Coesel wrote: >> John Larkin <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: >> >>> On Wed, 30 Sep 2009 16:29:03 GMT, nico(a)puntnl.niks (Nico Coesel) >>> wrote: >>> >>>> John Larkin <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: >>>> >>>>> On Tue, 29 Sep 2009 12:53:36 -0700, Joerg <invalid(a)invalid.invalid> >>>>> wrote: >>>>> >>>>> >>>>> There are some little USB samplers, but they're very expensive. >>>> What amount do you consider expensive? >>> $12K is expensive. >> >> Expensive indeed. Any idea what makes these buggers so expensive? >> > >The usual. High NRE costs, low sales volume, combined with the desire to >make a living. Yup, but if you have some sort of standard platform you could design a high bandwidth sampling front-end for it without much additional costs. That's how I setup my USB DSO project. -- Failure does not prove something is impossible, failure simply indicates you are not using the right tools... "If it doesn't fit, use a bigger hammer!" --------------------------------------------------------------
From: Joerg on 1 Oct 2009 16:28 JosephKK wrote: > On Tue, 29 Sep 2009 20:00:49 -0700, John Larkin > <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: > >> On Tue, 29 Sep 2009 15:27:53 -0700, Joerg <invalid(a)invalid.invalid> >> wrote: >> >>> John Larkin wrote: >>>> On Tue, 29 Sep 2009 12:53:36 -0700, Joerg <invalid(a)invalid.invalid> >>>> wrote: >>>> >>>>> John Larkin wrote: >>>>>> On Tue, 29 Sep 2009 13:34:14 -0400, Phil Hobbs >>>>>> <pcdhSpamMeSenseless(a)electrooptical.net> wrote: >>>>>> >>>>>>> John Larkin wrote: >>>>>>>> On Tue, 29 Sep 2009 09:25:15 -0700, Joerg <invalid(a)invalid.invalid> >>>>>>>> wrote: >>>>>>>> >>>>>>>>> John Larkin wrote: >>>>>>>>>> On Mon, 28 Sep 2009 17:43:22 -0700, Joerg <invalid(a)invalid.invalid> >>>>>>>>>> wrote: >>>>>>>>>> >>>>>>>>>>> John Larkin wrote: >>>>>>>>>>>> On Mon, 28 Sep 2009 20:05:23 -0400, Phil Hobbs >>>>>>>>>>>> <pcdhSpamMeSenseless(a)electrooptical.net> wrote: >>>>>>>>>>>> >>>>>>>>>>>>> John Fields wrote: >>>>>>>>>>>>>> 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. >>>>>>>>>>>>>> --- >>>>>>>>>>>>>> Re. switching, From: >>>>>>>>>>>>>> >>>>>>>>>>>>>> http://en.wikipedia.org/wiki/PIN_diode >>>>>>>>>>>>>> >>>>>>>>>>>>>> "Under zero or reverse bias, a PIN diode has a low capacitance. The low >>>>>>>>>>>>>> capacitance will not pass much of an RF signal. Under a forward bias of >>>>>>>>>>>>>> 1 mA, a typical PIN diode will have an RF resistance of about 1 ohm, >>>>>>>>>>>>>> making it a good RF conductor. Consequently, the PIN diode makes a good >>>>>>>>>>>>>> RF switch." >>>>>>>>>>>>>> --- >>>>>>>>>>>>> Good, but not fast. PIN diodes specialize in having a lot of stored >>>>>>>>>>>>> charge, so that the signal current can be quite a bit larger than the DC >>>>>>>>>>>>> current without causing excessive distortion. >>>>>>>>>>>>> >>>>>>>>>>>>> Cheers >>>>>>>>>>>>> >>>>>>>>>>>>> Phil Hobbs >>>>>>>>>>>> PINs stop behaving like PINs at low frequencies, too. So they don't >>>>>>>>>>>> make useful wideband switches. >>>>>>>>>>>> >>>>>>>>>>> Got to watch the carrier lifetime. The lower the bottom of your spectrum >>>>>>>>>>> and the higher the RF current, the longer its carrier lifetime must be. >>>>>>>>>>> I found PIN diodes to be great and most of all cheap variable >>>>>>>>>>> attenuators as well as switched. Designed in tons of them. >>>>>>>>>>> >>>>>>>>>>> >>>>>>>>>>>> But I meant active switching when I was referring to a TD. A TD would >>>>>>>>>>>> *generate* a fast step from an arbitrarily slow drive. >>>>>>>>>>>> >>>>>>>>>>> I've drooled over SRDs all my life and every time I wanted to buy one I >>>>>>>>>>> either couldn't have one or it was outlandishly expensive. Guess >>>>>>>>>>> avalanching is the only game in town and if you want avalanche-rated >>>>>>>>>>> then a bone-simple BJT can easily shoot up to twenty bucks. >>>>>>>>>> SRDs aren't hard to get. MA/Com has distributor parts, under a buck. >>>>>>>>>> M-Pulse and Metelics are good about samples. If you want a few, send >>>>>>>>>> me a SASE. >>>>>>>>>> >>>>>>>>>> Oh, here it is... >>>>>>>>>> >>>>>>>>>> 229-1769 DIO SRD 30V SOT23 150PS MA44769 1PF >>>>>>>>>> >>>>>>>>>> MA44769-287 PENSTOCK >>>>>>>>>> >>>>>>>>>> Price 58 cents in small quantities. >>>>>>>>>> >>>>>>>>>> They also have MA44767-287, 600 ps risetime, a little easier to drive >>>>>>>>>> because it stores more charge. >>>>>>>>>> >>>>>>>>>> These make nice edge generators and frequency multipliers. I have a >>>>>>>>>> rubidium clock that generates the 6.3846826128 GHz frequency from a 10 >>>>>>>>>> MHz rock with an absurdly small number of cheap parts. >>>>>>>>>> >>>>>>>>> Thanks, John! That's a decent price. And thanks for the SASE offer, but >>>>>>>>> maybe I'll combine that with a beer at Zeitgeist when I get down there :-) >>>>>>>> Well, drop in. We have a zillion exotic parts in stock. And the >>>>>>>> quality of Z's burgers has improved radically lately. Only biker bar I >>>>>>>> know of with Chimay on tap. >>>>>>>> >>>>>>>>> As a kid I grew up in Europe and back then such exotic parts were very >>>>>>>>> hard to find over there, even at hamfests. >>>>>>>> We were lucky. Tons of exotic surplus gear, lots of old teevees, >>>>>>>> Allied and Lafayette and Fair Radio Sales mail-order available to >>>>>>>> anyone, local distributors for over-the-counter transistors and >>>>>>>> 10-turn pots and such... the counter guys gave me more parts than I >>>>>>>> ever paid for. I made a deal with my parents to dump my allowance in >>>>>>>> favor of a revolving credit account with Allied, so I could just order >>>>>>>> stuff. I made spending money fixing radios and TVs. >>>>>>>> >>>>>>>> John >>>>>>>> >>>>>>> Still not as good as now. I just bought an excellent-condition HP 8568B >>>>>>> spectrum analyzer for $900. About 2 cents on the dollar. So far this >>>>>>> year I've bought test equipment that would have cost way over $100000 >>>>>>> new, for probably $4k altogether. Amazing. >>>>>>> >>>>>>> Cheers >>>>>>> >>>>>>> Phil Hobbs >>>>>> And I'm looking at, theoretically, a quarter million dollars worth of >>>>>> sampling heads over there on my shelf. This is an amazing time to >>>>>> start a niche business, or even an exotic hobby. >>>>>> >>>>> Is there anything available at reasonable cost that does zippy sampling >>>>> without needing a Goliath of a scope attached to it? >>>> Not really. The 5000 and 7000 series scopes had sampling plugins - I >>>> have a bunch, and they're dirt cheap now - but they were pretty bad >>>> compared to the superb 11801-series stuff. >>>> >>> There is an 11802 on Ebay right now for $1k but untested, "powers up". >>> Thing is, I haven't gotten much more space here. A sampler for the 7704 >>> over here would be nice. What is so bad with S-4 and 7S11? Ok, the >>> 25psec risetime doesn't quite rival your gear but for most stuff that >>> should do. >> That stuff works, but it's not as quantitative as the later gear. And >> TDR is a fabulous thing to have, and the TDR on the 7-series stuff is >> really mediocre. >> >> Isn't this beautiful? >> >> ftp://jjlarkin.lmi.net/Z250A.jpg >> ftp://jjlarkin.lmi.net/Z250_TDR.jpg >> >> (TDR of the test trace, J28 to J29) >> >>> >>>> There are some little USB samplers, but they're very expensive. >>>> >>> Probably not much of a market anymore and the TDR guys in the field >>> dont' need a precision under a foot to figure where they have to drop >>> the bucket of their Kubota. >> Too much cheap surplus stuff on ebay, too. I'd love to do a cheapish >> USB TDR, but there's probably no good market. >> >> John > > John L, Jeorg: > > I am in the market for (in no particular order) a fast analog scope > maybe a TEK 2465B. I could use an 11801/11802 with a few heads good > to say 6 GHz, and some probes. A decent freq/interval counter. A > 5-1/2 digit multimeter (with 4 terminal ohms, and true rms ac > measurements up to 100 KHz). And an AM/FM modulatable function/sweep > generator up to 20 MHz. Except for the good scopes, this is high > hobbyist to low end or mid-range lab stuff. > > 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. For the generator check out modulateable DDS eval boards. If you really don't want EBay your only options are 2nd hand re-sellers (expensive, usually), company auctions (very good deals, got some of my stuff that way) and another very good source are hamfests. -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
From: Phil Hobbs on 1 Oct 2009 16:49 JosephKK wrote: > On Tue, 29 Sep 2009 20:00:49 -0700, John Larkin > <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: > >> On Tue, 29 Sep 2009 15:27:53 -0700, Joerg <invalid(a)invalid.invalid> >> wrote: >> >>> John Larkin wrote: >>>> On Tue, 29 Sep 2009 12:53:36 -0700, Joerg <invalid(a)invalid.invalid> >>>> wrote: >>>> >>>>> John Larkin wrote: >>>>>> On Tue, 29 Sep 2009 13:34:14 -0400, Phil Hobbs >>>>>> <pcdhSpamMeSenseless(a)electrooptical.net> wrote: >>>>>> >>>>>>> John Larkin wrote: >>>>>>>> On Tue, 29 Sep 2009 09:25:15 -0700, Joerg <invalid(a)invalid.invalid> >>>>>>>> wrote: >>>>>>>> <giant snip> >>>>>>>>> As a kid I grew up in Europe and back then such exotic parts were very >>>>>>>>> hard to find over there, even at hamfests. >>>>>>>> We were lucky. Tons of exotic surplus gear, lots of old teevees, >>>>>>>> Allied and Lafayette and Fair Radio Sales mail-order available to >>>>>>>> anyone, local distributors for over-the-counter transistors and >>>>>>>> 10-turn pots and such... the counter guys gave me more parts than I >>>>>>>> ever paid for. I made a deal with my parents to dump my allowance in >>>>>>>> favor of a revolving credit account with Allied, so I could just order >>>>>>>> stuff. I made spending money fixing radios and TVs. >>>>>>>> >>>>>>>> John >>>>>>>> >>>>>>> Still not as good as now. I just bought an excellent-condition HP 8568B >>>>>>> spectrum analyzer for $900. About 2 cents on the dollar. So far this >>>>>>> year I've bought test equipment that would have cost way over $100000 >>>>>>> new, for probably $4k altogether. Amazing. >>>>>>> >>>>>>> Cheers >>>>>>> >>>>>>> Phil Hobbs >>>>>> And I'm looking at, theoretically, a quarter million dollars worth of >>>>>> sampling heads over there on my shelf. This is an amazing time to >>>>>> start a niche business, or even an exotic hobby. >>>>>> >>>>> Is there anything available at reasonable cost that does zippy sampling >>>>> without needing a Goliath of a scope attached to it? >>>> Not really. The 5000 and 7000 series scopes had sampling plugins - I >>>> have a bunch, and they're dirt cheap now - but they were pretty bad >>>> compared to the superb 11801-series stuff. >>>> >>> There is an 11802 on Ebay right now for $1k but untested, "powers up". >>> Thing is, I haven't gotten much more space here. A sampler for the 7704 >>> over here would be nice. What is so bad with S-4 and 7S11? Ok, the >>> 25psec risetime doesn't quite rival your gear but for most stuff that >>> should do. >> That stuff works, but it's not as quantitative as the later gear. And >> TDR is a fabulous thing to have, and the TDR on the 7-series stuff is >> really mediocre. >> >> Isn't this beautiful? >> >> ftp://jjlarkin.lmi.net/Z250A.jpg >> ftp://jjlarkin.lmi.net/Z250_TDR.jpg >> >> (TDR of the test trace, J28 to J29) >> >>> >>>> There are some little USB samplers, but they're very expensive. >>>> >>> Probably not much of a market anymore and the TDR guys in the field >>> dont' need a precision under a foot to figure where they have to drop >>> the bucket of their Kubota. >> Too much cheap surplus stuff on ebay, too. I'd love to do a cheapish >> USB TDR, but there's probably no good market. >> >> John > > John L, Jeorg: > > I am in the market for (in no particular order) a fast analog scope > maybe a TEK 2465B. I could use an 11801/11802 with a few heads good > to say 6 GHz, and some probes. A decent freq/interval counter. A > 5-1/2 digit multimeter (with 4 terminal ohms, and true rms ac > measurements up to 100 KHz). And an AM/FM modulatable function/sweep > generator up to 20 MHz. Except for the good scopes, this is high > hobbyist to low end or mid-range lab stuff. > > 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. FWIW here's my lab equipment list including what I paid for it on eBay. Some things I already had for awhile and forgot, or else didn't get on eBay. I've had really good luck on eBay--good stuff for a few cents on the dollar, almost zero duds. Cheers Phil Hobbs ------------- ElectroOptical Innovations Equipment List Phil Hobbs, September 29, 2009 HAVES ***** Oscilloscopes: Price (Shipping) -------------- Tek TDS744A 500 MHz 2Gs/s, 4 channel scope $ 849 ( 0) Tek 11802 Sampling Scope SD-22 12.5 GHz dual low noise head SD-24 20 GHz dual TDR head SD-42 6.4 GHz OE converter $ 200 SD-14 dual-channel probe sampler 3 GHz $ 175 ( 16) (One channel mildly broken) Tektronix 466 Analogue Storage Scope $ 100 Tektronix 475A Analogue Scope $ 100 Counters and Spectrum Analyzers ------------------------------- HP 8568B Spectrum Analyzer, 100 Hz->1.5 GHz $ 900 ( 90) HP 35665A dynamic signal analyzer $ 351 ( 120) (Options 1C1 (add 2MB memory), 1D4 (Arbitrary function source), and 1C2 (HP instrument BASIC) HP 5315B Universal Counter $ 80 Signal Sources / Time & Frequency Generators --------------------------------------------- HP 8013B pulser Highland P400 Digital delay generator HP 3325A synthesizer $ 299 HP 8640B ultraquiet phaselocked generator $ 120 ( 60) HP 8620C Sweeper mainframe $ 250 ( 50) HP 86222B 0.01-2.4 GHz plugin Meters ------- HP 400EL AC Voltmeter (10 MHz) HP 3403A True RMS Voltmeter (100 MHz) $ 95 ( 26) Simpson Model 260 Series 3 multimeter Fluke 87 handheld DMM $ 249 ( 0) Keithley 191 5.5 digit DMM #1 Keithley 191 5.5 digit DMM #2 Power Supplies -------------- MIT PMT-2000 HV power supply $ 41 ( 13) Power Designs TP343A triple DC power supply $ 48 ( 16) Power Designs TP325 triple DC power supply $ 47 ( 17) HP 6112A Precision DC power supply (5 digit) Amplifiers ---------- Highland J750 Amplifier Highland T860 Buffer/Driver Optical Test Equipment ---------------------- Blue Sky model 200 Collimeter collimation tester Uniphase 1137P He-Ne (needs 1202 $ 212 ( 21) power supply, 2.4 kV, 6.5 mA) Furniture and Hardware ----------------------- 19-inch HP rack $ 300 ( 0) Vidmar 15-drawer cabinet $1382 ( 176) (new) Safco 5-drawer map cabinet, 30x48 $ 0 ( 0) Salvage 5 pcs 2M GPIB cables $ 32 ( 16) --------------------------------------------------------------- Total 5830 ( 621) -------------- WANTS ------------------ Tools ----- Cooper 13006C 6-inch gas pliers (13006 OK too)--discontinued Mantis microscope with 4x & 8X objectives $1500 Sherline--Small lathe/milling machine $3000 Metcal soldering/desoldering station $ 300 Small electric vacuum pump $ 150 Small electric compressor $ 150 Spares ------ Epson SMD-300 disc drive for HP 35660A (?) TEAC 300D disc drives for HP 35665A Sony MP-F52W-20 disc drives for HP 4145B Interfacing and Control ----------------------- Prologix GPIB-Ethernet module $ 200 new Oscilloscopes & Accessories --------------------------- Tek TDS684B 1 GHz, 5 Gs/s, 4 channels simultaneously, colour LCD Opt 13 serial/parallel hardcopy port Opt 1F Floppy drive Opt 2F Advanced waveform math For Tek 11802 sampling scope: SD-46 20 GHz OE converter SD-48 30 GHz OE converter SD-32 50 GHz sampling head SD-51 20 GHz trigger head 1x 012-1220-00 1m sampling head extender 1x 012-1221-00 2m sampling head extender Counters and Spectrum Analyzers ------------------------------- HP 8444A Opt 59 Tracking Generator for 8568B HP 5372A Modulation domain analyzer Meters ------ HP 435A analog power meter HP 8482A power meter head and cable (100 kHz - 4 GHz) HP 8484A diode power head and 11708A reference attenuator HP 4470A transistor noise tester Signal Sources / Time & Frequency Generators -------------------------------------------- HP 3325B or equivalent HP 8560D synth plus plugins Highland Technology arbs Furniture --------- Lista or Vidmar two-pedestal workbench with lots of small drawers Workbench for Sherline Optical -------- 3 x 4 foot Newport optical breadboard and bench 10 mW He-Ne 100-mW single frequency green DP YAG Lots of mounts Optical spectrum analyzer Optical power meter Pb salt camera JDS Uniphase 1202-1 power supply Computers --------- 26-processor pizza box cluster, 50G RAM, 10 TB disc, Rocks cluster Linux Small server rack 1U 20-inch LCD/keyboard drawer GbE router Intel C++ and Fortran compilers Business FIOS line--15/20Mb fixed IP Firewall machine NAS machine with mirroring B-size laser printer with Postscript, Ethernet and duplex--HP 5000, about $300-400 refurb B-size page scanner with ADF & duplex -- Dr Philip C D Hobbs Principal ElectroOptical Innovations 55 Orchard Rd Briarcliff Manor NY 10510 845-480-2058 hobbs at electrooptical dot net http://electrooptical.net
From: Nico Coesel on 1 Oct 2009 17:21 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. -- Failure does not prove something is impossible, failure simply indicates you are not using the right tools... "If it doesn't fit, use a bigger hammer!" --------------------------------------------------------------
From: Nico Coesel on 1 Oct 2009 17:28
Phil Hobbs <pcdhSpamMeSenseless(a)electrooptical.net> wrote: > >Tek 11802 Sampling Scope > SD-22 12.5 GHz dual low noise head > SD-24 20 GHz dual TDR head > SD-42 6.4 GHz OE converter $ 200 > SD-14 dual-channel probe sampler 3 GHz $ 175 ( 16) > (One channel mildly broken) That seems very reasonable especially since the Dollar is so low. Shipping costs to Europe are still huge though. -- Failure does not prove something is impossible, failure simply indicates you are not using the right tools... "If it doesn't fit, use a bigger hammer!" -------------------------------------------------------------- |