On 02/24/2018 06:29 PM, Phil Hobbs wrote:> On 02/24/2018 06:23 PM, JM wrote: >> On 23/02/2018 17:11, Phil Hobbs wrote: >>> On 02/23/2018 11:15 AM, JM wrote: >>>> On 21/02/2018 01:29, pcdhobbs@gmail.com wrote: >>>>>> I have written a program that controls that thing over the network >>>>>> and measures spectra from 0.1 Hz to 1MHz, one FFT per decade, reads >>>>>> the results, combines them and plots them with gnuplot. >>>>> >>>>>> One needs a converter box from coax ethernet to contemporary network, >>>>>> then one just opens port 5000-something on 192.168.178.111 and simply >>>>>> reads and writes GPIB-strings. And the coax needs 2 terminations, >>>>>> even >>>>>> when the "cable" is only 5 inch long. :-) >>>>> >>>>>> No need for GPIB cards and semi-supported drivers. >>>>> >>>>>> These measurements of voltage regulator noise have been done with it: >>>>> < >>>>> https://www.flickr.com/photos/137684711@N07/24070698809/in/album-72157662535945536/ >>>>> >>>>> >>>>> > >>>>> >>>>> >>>>>> Just in case you win it and are interested. >>>>> >>>>> Hi, Gerhard, >>>>> >>>>> I did, and I am. I'll have to gin up a nice low-1/f-noise preamp for >>>>> it, but that'll be fun. >>>>> >>>>> Thanks >>>>> >>>>> Phil Hobbs >>>>> >>>> >>>> Note that the software options can easily be unlocked on these >>>> (although >>>> they would be of little use for your intended application). >>> >>> The cell-phone stuff won't help much, but I'm hoping that I can turn on >>> the AYB (spectrogram and waterfall) option without scrooching it. >> >> You'll be able to do that. >> >>> (Option AY8, the internal source, would be useful too, but it's probably >>> a HW option.) >>> >> >> Oh, you got an 89431A as well as a 89410A? You'll soon be welding a >> couple of 42H racks on top of each other to save on floor space. >> >>> The software one should be no big issue as long as the floppy drive >>> works reliably. >>> >>> Cheers >>> >>> Phil Hobbs >>> >> > I got the complete 89441A 2.65 GHz gizmo. I'll move my spare Tek11801C > out of the rack to make space. ;) > > You can fit a lot in a 7-foot EIA rack. >Speaking of which, I could use a shorter four-post instrument rack with adjustable rails, but they never seem to come up on eBay--just the flimsy audio and gigundo server racks. Any sourcing suggestions? I bought my present HP one from long-lost SED regular ecnerwal in about 2009. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com
FFT analyzer recommendations
Started by ●February 16, 2018
Reply by ●February 24, 20182018-02-24
Reply by ●February 24, 20182018-02-24
Phil Hobbs wrote:> > Any sourcing suggestions? I bought my present HP one from long-lost SED > regular ecnerwal in about 2009. >Hunt up an old Tek rolling cart. They have two vertical pillars which are std 19" wide opening. Good heavy duty cart with 600Lb smooth rool casters. Most come with shelves and drawers too (which can be re-sold if not desired).
Reply by ●February 24, 20182018-02-24
On 02/24/2018 08:09 PM, Long Hair wrote:> Phil Hobbs wrote: > >> >> Any sourcing suggestions? I bought my present HP one from long-lost SED >> regular ecnerwal in about 2009. >> > > Hunt up an old Tek rolling cart. They have two vertical pillars which > are std 19" wide opening. Good heavy duty cart with 600Lb smooth rool > casters. Most come with shelves and drawers too (which can be re-sold > if not desired). >I'm from back then too, so I remember them fondly. (Well, the 7000 series, not the 5XX tube monsters.) You couldn't fit a stack of 19" rack equipment on a 7000-series cart, because it's too narrow. I haven't used the ginormo tube-scope carts, but in general tippable carts are way too short and unstable. It's hard to see how you could get more than one or (at most) two large instruments on those before the tipping motion became dicey. I've got instruments on Ikea kitchen carts, which are fine, but I need a second real rack. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com
Reply by ●February 24, 20182018-02-24
Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote in news:arudnYqcBfI1jQ_HnZ2dnUU7-aPNnZ2d@supernews.com:> On 02/24/2018 08:09 PM, Long Hair wrote: >> Phil Hobbs wrote: >> >>> >>> Any sourcing suggestions? I bought my present HP one from long-lost >>> SED regular ecnerwal in about 2009. >>> >> >> Hunt up an old Tek rolling cart. They have two vertical pillars >> which >> are std 19" wide opening. Good heavy duty cart with 600Lb smooth >> rool casters. Most come with shelves and drawers too (which can be >> re-sold if not desired). >> > I'm from back then too, so I remember them fondly. (Well, the 7000 > series, not the 5XX tube monsters.) > > You couldn't fit a stack of 19" rack equipment on a 7000-series cart, > because it's too narrow. I haven't used the ginormo tube-scope carts, > but in general tippable carts are way too short and unstable. It's > hard to see how you could get more than one or (at most) two large > instruments on those before the tipping motion became dicey. > > I've got instruments on Ikea kitchen carts, which are fine, but I need > a second real rack. > > Cheers > > Phil Hobbs >These were not "tipping carts". These monsters could mount a friggin shuttle cockpit console. ;-) The K420 series. I have a couple that have five foot tall pillars on them. The casters are to die for in mobility terms. https://www.ebay.com/itm/Tektronix-K420-Instrument-Workstation- Cart/332365981238
Reply by ●February 25, 20182018-02-25
Floor space is a bit of an issue, because we've got a lot of good stuff: https://electrooptical.net/Lab_Tour/ https://electrooptical.net/Equipment So I really need a shorter version of the big HP rack in the photos. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com
Reply by ●February 25, 20182018-02-25
On 23/02/2018 20:17, Gerhard Hoffmann wrote:> Am 21.02.2018 um 02:29 schrieb pcdhobbs@gmail.com: > >> >> I did, and I am. I'll have to gin up a nice low-1/f-noise preamp for >> it, but that'll be fun. >> > > I'm working on a chopper preamp that should be flat down to at least > 100mHz, but it seems that I cannot verify that with the 89441A. > > It works with parallel ADG819 analog switches, step up transformers, > more low noise gain with ADA4898s on 500 KHz, synchronous demodulator > back to baseband and some more gain. > > A Xilinx Coolrunner II generates the timing from a 100 MHz osc. > It looks like I get 120 pV/rtHz. > > The main problem is the ringing of the step up transformer. I re-wired > some Macom and Pulse SMD transformers under the microscope using 50u wire. > > That was no fun. 1/2 :-) > > cheers, GerhardI designed a CSEM receiver 20 or so years ago with sub 100pV noise (0.01-15Hz BW and 120dB overall gain) with a similar architecture. These worked with Ag-AgCl field sensors with a source resistance of about 5 ohms. I'd expect modern CSEM receivers to have improved on that - a google or patent search might give you some ideas?
Reply by ●February 25, 20182018-02-25
JM wrote...> >On 23/02/2018 20:17, Gerhard Hoffmann wrote: >> Am 21.02.2018 um 02:29 schrieb pcdhobbs@gmail.com: >> >>> >>> I did, and I am. I'll have to gin up a nice low-1/f-noise preamp for >>> it, but that'll be fun. >>> >> >> I'm working on a chopper preamp that should be flat down to at least >> 100mHz, but it seems that I cannot verify that with the 89441A. >> >> It works with parallel ADG819 analog switches, step up transformers, >> more low noise gain with ADA4898s on 500 KHz, synchronous demodulator >> back to baseband and some more gain. >> >> A Xilinx Coolrunner II generates the timing from a 100 MHz osc. >> It looks like I get 120 pV/rtHz. > > I designed a CSEM receiver 20 or so years ago with sub 100pV noise > (0.01-15Hz BW and 120dB overall gain) with a similar architecture. > These worked with Ag-AgCl field sensors with a source resistance of > about 5 ohms.Just as a reminder, Paul and I made a simple 65 pV/rt-Hz preamp, all the how-to details reported in AoE III, pages 505 to 508. -- Thanks, - Win
Reply by ●February 25, 20182018-02-25
pcdhobbs@gmail.com wrote:> Floor space is a bit of an issue, because we've got a lot of good stuff: > > https://electrooptical.net/Lab_Tour/ > > https://electrooptical.net/Equipment > > So I really need a shorter version of the big HP rack in the photos. > > Cheers > > Phil Hobbs >Are you planning on using the rack as a mobile device? Because they are almost always fitted with small diameter hard casters. Those Tek carts, BTW can have heavy items fitted right down next to the floor. It ain't no scope cart. New ones sell for $1500. That is all we use in our labs. The last one had four in it, right before the boss moved.
Reply by ●February 25, 20182018-02-25
On 02/25/2018 11:43 AM, Long Hair wrote:> pcdhobbs@gmail.com wrote: > >> Floor space is a bit of an issue, because we've got a lot of good stuff: >> >> https://electrooptical.net/Lab_Tour/ >> >> https://electrooptical.net/Equipment >> >> So I really need a shorter version of the big HP rack in the photos.>> > > Are you planning on using the rack as a mobile device? > > Because they are almost always fitted with small diameter hard casters.If you look at the big rack, you'll find that it's sitting on a chunk of butcher block with large cast-iron cylindrical casters with heavy solid tires from McMaster-Carr. It rolls great. The smaller rack won't need such beefy wheels.> > Those Tek carts, BTW can have heavy items fitted right down next to > the floor. It ain't no scope cart. New ones sell for $1500. That is > all we use in our labs. The last one had four in it, right before the > boss moved.Carts I can get for cheap, but I really want a rack. Failing all else, I can get a couple of two-post relay racks and have some cross braces welded on, but there must be some of the old-timey ones rattling round out there. Maybe I'll do a road trip to the Dayton Hamfest this year. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com
Reply by ●February 25, 20182018-02-25
Phil Hobbs wrote:> On 02/25/2018 11:43 AM, Long Hair wrote: >> pcdhobbs@gmail.com wrote: >> >>> Floor space is a bit of an issue, because we've got a lot of good stuff: >>> >>> https://electrooptical.net/Lab_Tour/ >>> >>> https://electrooptical.net/Equipment >>> >>> So I really need a shorter version of the big HP rack in the photos. > >>> >> >> Are you planning on using the rack as a mobile device? >> >> Because they are almost always fitted with small diameter hard casters. > > If you look at the big rack, you'll find that it's sitting on a chunk of > butcher block with large cast-iron cylindrical casters with heavy solid > tires from McMaster-Carr. It rolls great. The smaller rack won't need > such beefy wheels. >> >> Those Tek carts, BTW can have heavy items fitted right down next to >> the floor. It ain't no scope cart. New ones sell for $1500. That is >> all we use in our labs. The last one had four in it, right before the >> boss moved. > > Carts I can get for cheap, but I really want a rack. Failing all else, > I can get a couple of two-post relay racks and have some cross braces > welded on, but there must be some of the old-timey ones rattling round > out there. Maybe I'll do a road trip to the Dayton Hamfest this year. > > Cheers > > Phil Hobbs >https://www.amazon.com/s/ref=nb_sb_noss?url=search-alias%3Daps&field-keywords=18+U+rack+enclosure
