"RBlack" <news@rblack01.plus.com> wrote in message news:MPG.30d213a96b2189b1989691@reader80.eternal-september.org...> > > What type is the input connector BTW? It doesn't appear to be a BNC > from the photos, it's threaded, similar to a N type but smaller and with > serrations on the mating face. The manual just describes it as a co-ax > connector. >The connector is an SO-239 (female), often called a UHF connector. Its mate is a PL-259 (male). They are very common and most often used for HF applications. For this a;application, the connectors need to use Teflon for the insulation and they are a bit rare.
Keithley 610C repair
Started by ●December 1, 2015
Reply by ●December 9, 20152015-12-09
Reply by ●December 9, 20152015-12-09
On Wed, 9 Dec 2015 10:32:46 -0000, RBlack <news@rblack01.plus.com> wrote:>What type is the input connector BTW? It doesn't appear to be a BNC >from the photos, it's threaded, similar to a N type but smaller and with >serrations on the mating face. The manual just describes it as a co-ax >connector.The early instruments used a Teflon insulated UHF connector. Later models use a BNC-based triax connector and triaxial cable. If the one you're looking at has threads on the outside but is obviously not a UHF connector, then you're probably looking at one of the special nuclear variations designed to read the ion current from neutron detectors in power plants. That would be a C-based connector. I've never seen it anywhere else so it's probably a Keithley-only item. I have also a variation that has conventional banana binding posts with a driven guard terminal. That variation works almost as well as the triax-based one except where RFI is present. The Triax cable is quite special, having a graphite coating on the surface of each layer of dielectric to reduce the triboelectric generation to practically zero. It works quite well but is extremely expensive and AFIK the only source is Keithley. John John DeArmond http://www.neon-john.com http://www.fluxeon.com Tellico Plains, Occupied TN See website for email address
Reply by ●December 9, 20152015-12-09
On 12/09/2015 11:41 AM, Neon John wrote:> On Wed, 9 Dec 2015 10:32:46 -0000, RBlack <news@rblack01.plus.com> > wrote: > > >> What type is the input connector BTW? It doesn't appear to be a BNC >>from the photos, it's threaded, similar to a N type but smaller and with >> serrations on the mating face. The manual just describes it as a co-ax >> connector. > > The early instruments used a Teflon insulated UHF connector. Later > models use a BNC-based triax connector and triaxial cable. > > If the one you're looking at has threads on the outside but is > obviously not a UHF connector, then you're probably looking at one of > the special nuclear variations designed to read the ion current from > neutron detectors in power plants. That would be a C-based connector. > I've never seen it anywhere else so it's probably a Keithley-only > item. > > I have also a variation that has conventional banana binding posts > with a driven guard terminal. That variation works almost as well as > the triax-based one except where RFI is present. > > The Triax cable is quite special, having a graphite coating on the > surface of each layer of dielectric to reduce the triboelectric > generation to practically zero. It works quite well but is extremely > expensive and AFIK the only source is Keithley.You can probably mimic it adequately by ripping the jacket off a piece of RG58, rubbing graphite into the braid, then putting some heat shrink on. I doubt there's much motion between the centre conductor and the dielectric. I usually use RG402 for that sort of stuff. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 hobbs at electrooptical dot net http://electrooptical.net
Reply by ●December 9, 20152015-12-09
On Wednesday, December 9, 2015 at 2:32:59 AM UTC-8, RBlack wrote:> ... without access to another instrument at least as capable as > the 610C I would have no confidence I hadn't screwed up the repair. The > next-best meter I have is a 34410A which (IIRC) can resolve hundreds of > nanoamps and up to 10 megohms.It isn't hard for low current; just a low-leakage capacitor and a slow ramp generator, and you have a low-current reference. Some way to discharge the capacitor (clipleads and teflon turret terminals?) is needed. Teflon and some ceramics are the best capacitor types; 100 pF gives you Iout = (1e-10) dV/dt and I've made ramp generators that did about 10 mv/hour, and can keep it up all day. that'd be Iout in the 3e-16 amps range... You calibrate the ramp generator with a DVM and stopwatch.
Reply by ●December 10, 20152015-12-10
>Teflon and some ceramics are the best capacitor types; 100 pF >gives youIout = �(1e-10) dV/dt>and I've made ramp generators that did about 10 mv/hour, and can keep >it up all day. � that'd be Iout in the 3e-16 amps range...HP 3325As make nice ramps down to 1 uHz, and they're nearly as cheap as 610Cs. It's not a modern DDS/arb architecture, so I don't think its output is a staircase. Cheers Phil Hobbs
Reply by ●December 10, 20152015-12-10
On Thu, 10 Dec 2015 05:11:41 -0800 (PST), Phil Hobbs <pcdhobbs@gmail.com> wrote:>>Teflon and some ceramics are the best capacitor types; 100 pF >>gives you >Iout = �(1e-10) dV/dt >>and I've made ramp generators that did about 10 mv/hour, and can keep >>it up all day. � that'd be Iout in the 3e-16 amps range... > >HP 3325As make nice ramps down to 1 uHz, and they're nearly as cheap as 610Cs. It's not a modern DDS/arb architecture, so I don't think its output is a staircase. > > >Cheers > >Phil HobbsYou could charge a 10 uF cap through a 1G resistor, and couple that into a picoammeter through a 10 pF cap. 10 volts makes 10 nA which becomes 10 fA. -- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
Reply by ●December 10, 20152015-12-10
On 12/10/2015 01:41 PM, John Larkin wrote:> On Thu, 10 Dec 2015 05:11:41 -0800 (PST), Phil Hobbs > <pcdhobbs@gmail.com> wrote: > >>> Teflon and some ceramics are the best capacitor types; 100 pF >>> gives you >> Iout = (1e-10) dV/dt >>> and I've made ramp generators that did about 10 mv/hour, and can keep >>> it up all day. that'd be Iout in the 3e-16 amps range... >> >> HP 3325As make nice ramps down to 1 uHz, and they're nearly as cheap as 610Cs. It's not a modern DDS/arb architecture, so I don't think its output is a staircase. >> >> >> Cheers >> >> Phil Hobbs > > You could charge a 10 uF cap through a 1G resistor, and couple that > into a picoammeter through a 10 pF cap. 10 volts makes 10 nA which > becomes 10 fA. > > > >Ceramic caps that big are pretty nonlinear to use for calibration, no? I have some 2-uf 200V dogbone mylars. When my 610C gets here this evening I'll test their insulation resistance. ;) An LM662 triangle wave generator with one of your patented bootstrapped-voltage-references could go pretty slowly. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 hobbs at electrooptical dot net http://electrooptical.net
Reply by ●December 10, 20152015-12-10
On Thu, 10 Dec 2015 13:46:24 -0500, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:>On 12/10/2015 01:41 PM, John Larkin wrote: >> On Thu, 10 Dec 2015 05:11:41 -0800 (PST), Phil Hobbs >> <pcdhobbs@gmail.com> wrote: >> >>>> Teflon and some ceramics are the best capacitor types; 100 pF >>>> gives you >>> Iout = (1e-10) dV/dt >>>> and I've made ramp generators that did about 10 mv/hour, and can keep >>>> it up all day. that'd be Iout in the 3e-16 amps range... >>> >>> HP 3325As make nice ramps down to 1 uHz, and they're nearly as cheap as 610Cs. It's not a modern DDS/arb architecture, so I don't think its output is a staircase. >>> >>> >>> Cheers >>> >>> Phil Hobbs >> >> You could charge a 10 uF cap through a 1G resistor, and couple that >> into a picoammeter through a 10 pF cap. 10 volts makes 10 nA which >> becomes 10 fA. >> >> >> >> > >Ceramic caps that big are pretty nonlinear to use for calibration, no? >I have some 2-uf 200V dogbone mylars. When my 610C gets here this >evening I'll test their insulation resistance. ;)A 10 pF NPO should be pretty good on the output side. I'd use a film cap for the big one.> >An LM662 triangle wave generator with one of your patented >bootstrapped-voltage-references could go pretty slowly. >Yeah, if you want a linear ramp a bootstrap current source is a good way to go, almost the only way to go if you want, say, 1 nA. Film cap, cmos opamp follower, bandgap level shifter, 1G resistor back to the cap. Reset it with a paper clip. -- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
Reply by ●December 10, 20152015-12-10
On 12/10/2015 03:51 PM, John Larkin wrote:> On Thu, 10 Dec 2015 13:46:24 -0500, Phil Hobbs > <pcdhSpamMeSenseless@electrooptical.net> wrote: > >> On 12/10/2015 01:41 PM, John Larkin wrote: >>> On Thu, 10 Dec 2015 05:11:41 -0800 (PST), Phil Hobbs >>> <pcdhobbs@gmail.com> wrote: >>> >>>>> Teflon and some ceramics are the best capacitor types; 100 pF >>>>> gives you >>>> Iout = (1e-10) dV/dt >>>>> and I've made ramp generators that did about 10 mv/hour, and can keep >>>>> it up all day. that'd be Iout in the 3e-16 amps range... >>>> >>>> HP 3325As make nice ramps down to 1 uHz, and they're nearly as cheap as 610Cs. It's not a modern DDS/arb architecture, so I don't think its output is a staircase. >>>> >>>> >>>> Cheers >>>> >>>> Phil Hobbs >>> >>> You could charge a 10 uF cap through a 1G resistor, and couple that >>> into a picoammeter through a 10 pF cap. 10 volts makes 10 nA which >>> becomes 10 fA. >>> >>> >>> >>> >> >> Ceramic caps that big are pretty nonlinear to use for calibration, no? >> I have some 2-uf 200V dogbone mylars. When my 610C gets here this >> evening I'll test their insulation resistance. ;) > > A 10 pF NPO should be pretty good on the output side. I'd use a film > cap for the big one. > > >> >> An LM662 triangle wave generator with one of your patented >> bootstrapped-voltage-references could go pretty slowly. >> > > Yeah, if you want a linear ramp a bootstrap current source is a good > way to go, almost the only way to go if you want, say, 1 nA. > > Film cap, cmos opamp follower, bandgap level shifter, 1G resistor back > to the cap. Reset it with a paper clip.The $125 610C arrived just now, by UPS ground all the way from SoCal. At first blush, it looks like it works pretty well. It zeroes fine, which is one of the main indications of health. No trace of stickiness in the meter movement, which is another important indication. On the 10 fA FS range, with the input disconnected but with the cap off the connector, waving my hand a foot away from the front panel makes the meter move all over the place. Works on both the slow and fast settings. Very pretty! Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 hobbs at electrooptical dot net http://electrooptical.net
Reply by ●December 11, 20152015-12-11
On 12/10/2015 07:25 PM, Phil Hobbs wrote:> On 12/10/2015 03:51 PM, John Larkin wrote: >> On Thu, 10 Dec 2015 13:46:24 -0500, Phil Hobbs >> <pcdhSpamMeSenseless@electrooptical.net> wrote: >> >>> On 12/10/2015 01:41 PM, John Larkin wrote: >>>> On Thu, 10 Dec 2015 05:11:41 -0800 (PST), Phil Hobbs >>>> <pcdhobbs@gmail.com> wrote: >>>> >>>>>> Teflon and some ceramics are the best capacitor types; 100 pF >>>>>> gives you >>>>> Iout = (1e-10) dV/dt >>>>>> and I've made ramp generators that did about 10 mv/hour, and can keep >>>>>> it up all day. that'd be Iout in the 3e-16 amps range... >>>>> >>>>> HP 3325As make nice ramps down to 1 uHz, and they're nearly as >>>>> cheap as 610Cs. It's not a modern DDS/arb architecture, so I don't >>>>> think its output is a staircase. >>>>> >>>>> >>>>> Cheers >>>>> >>>>> Phil Hobbs >>>> >>>> You could charge a 10 uF cap through a 1G resistor, and couple that >>>> into a picoammeter through a 10 pF cap. 10 volts makes 10 nA which >>>> becomes 10 fA. >>>> >>>> >>>> >>>> >>> >>> Ceramic caps that big are pretty nonlinear to use for calibration, no? >>> I have some 2-uf 200V dogbone mylars. When my 610C gets here this >>> evening I'll test their insulation resistance. ;) >> >> A 10 pF NPO should be pretty good on the output side. I'd use a film >> cap for the big one. >> >> >>> >>> An LM662 triangle wave generator with one of your patented >>> bootstrapped-voltage-references could go pretty slowly. >>> >> >> Yeah, if you want a linear ramp a bootstrap current source is a good >> way to go, almost the only way to go if you want, say, 1 nA. >> >> Film cap, cmos opamp follower, bandgap level shifter, 1G resistor back >> to the cap. Reset it with a paper clip. > > > The $125 610C arrived just now, by UPS ground all the way from SoCal. At > first blush, it looks like it works pretty well. It zeroes fine, which > is one of the main indications of health. No trace of stickiness in the > meter movement, which is another important indication. > > On the 10 fA FS range, with the input disconnected but with the cap off > the connector, waving my hand a foot away from the front panel makes the > meter move all over the place. > > Works on both the slow and fast settings. > > Very pretty! >Resistance reads about 2% low up to 1E12 ohms, calibrated using a 5-1/2 digit, 10M DVM and a 10V HP precision power supply. A Russian 1 teraohm 10% resistor reads about 0.86 Tohms on the 610C and about 0.89 Tohms using the digital voltmeter trick. The fast setting pegs the meter in the resistance mode. (I didn't try re-zeroing it.) Voltage is within 1% where I looked. Stability is excellent--on the 10 fA FS range, it stays zeroed to within 1% of FS over several minutes, and that's after only about half an hour of warm-up. With a 100 pF polystyrene cap across the input (just so I know roughly what the capacitance is there), and measuring the 0-3V output on the back near full scale (2.986V), the voltage decay is less than 100 uV/min and is consistent with zero. That means the input current on the 10V range is less than 100uV * 10V/3V * 100 pF /60 s = 0.5 fA. Amazing. (Not bad on the polystyrene, either.) I measured a 2.2 uF 600V wound mylar, charged to 10V for a few seconds. On the 10-V range, it produced nearly full scale on the 0-3V DC output. This output dropped about 220uV out of 3V in 3 minutes, for a self-discharge time constant of about 2.4 million seconds (about a month). So with a 47 G resistor and an LM662, you could actually make a decent 10 microhertz sawtooth out of it. Not a bad gizmo for $125 plus $25 shipping! Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 hobbs at electrooptical dot net http://electrooptical.net
