Re: [volt-nuts] Bohnenberger electrometer
I once made the alu-foil type but also one with a jfet. The gate as "antenna" I have many meters but no static field elctrometer. (and no coulomb meter, never seen one in real life too) I like exotic meters. I repaired (and modded) a 3 axis fluxgate meter a while back. The owner uses it to measure magnetic fields (has to do with installing SEM microscopes, he does this all over the world. Fred PA4TIM On 03/16/2018 01:52 PM, Dr. David Kirkby wrote: On 6 March 2018 at 09:40, Dr. David Kirkby <drkir...@kirkbymicrowave.co.uk> wrote: Sorry this is not precision voltage measurement, but it is not unrelated. As a radio club project, we are building a simple electroscope, with no active components. The gold leave variety would work, but two bits of alluminum foil do too. My plan was to go one better, and build a Bohnenberger electrometer. For what it is worth, this is my design: http://www.kirkbymicrowave.co.uk/tmp/G8WRBs-electrometer.jpg There's 600 V DC between two strips of PCB material. A 600 V 47 uF capacitor was charged to 600 V. A small bit of aluminum foil, between the plates, then moves to the left or right, depending on whether the charge is positive or negative. The big capacitor, which is 2.2 nF 15 kV is not doing much apart from being a structure to hold other parts. It has large lugs on it, where multiple M6 screws can be fitted, so it is nice electrical insulator. Its actual capacitance (2.2 nF) is insignificant when in parallel with 47 uF. Under sufficient applied field, and with sufficient charge, it is possible to get the foil to oscillate from side to side like a pendulum. I believe what happens is if a negative charge is applied to the foil, it gets attracted to the positive plate, which causes them to touch, so the foil receives a positive charge - the opposite of what it had before. This causes it to move in the other direction. It is possible to get it to oscillate back and forth. I expect, with a sufficient mass and very high electric field, a pendulum could be made to make a clock, but with a little bit of tin foil, the foil would clearly break quite quickly. A more substantial structure would be required, which I suspect would need some very high voltages. A Google of 'electrostatic clocks' does indicate they exist, although I have not looked into how they work. But I believe a sufficiently high electric field could make a pendulum swing, and that of course could make a clock. Anyway, it was interesting playing with this. I am wondering if there's any way to detect the polarity of a charge, without having any power source. Clearly the gold leaf electroscope can detect charge, but does not need a power supply. The Bohnenberger electrometer can detect polarity too, but needs a power supply. I was wondering if the charge could be applied to two diodes, which were each connected to a plate. The it may be possible to charge one plate only, as only one diode would conduct, so only one plate would be charged. The the leaf would be repelled from whatever plate has the same charge. Dave ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] Datron 4700 manual and options
The 4700 is fixed. The 400V issue was caused by missing -15V, That was caused by a shorted tantalum on the Ohms board. It was less then 0,1 ohm but not even discolored. I was curious about the way they die. So a desoldered about 20 tantalums and measured C, D and leakage current. New ones have a very low D, at 1 kHz well under 0,1. Capacitance did not decrease much like electrolytics do, but D does increase over age. Leakage current is as good as zero, (my best leakage tester has only 1 uA resolution so it can not measure leakage in the nA's) The worst D i found was 0.67. They did not leak, so I think they go from good to short in one step. capacitance does not seem to decrease. In electrolytics this is caused by a decreasing oxidelayer caused by the decreasing electrolyte. I replaced a few by electrolytics as a test. The D factor of the 10uF low ESR panasonic FM caps was better as that of the new 10uF tantalums I had. Most tantalums measured OK, a few had very high D, non of them leaked DC. So I think (based on this to small number test) they get a high D, start to dissipate and as a result of that develop a short. Fred On 07/21/2017 01:59 AM, Todd Micallef wrote: Fred, I used the same values and typically went up to the next higher voltage. I think most ended up as 35v since I bought them in quantity. Some people recommend the OS-CON family as replacements. Many of the failed tantalums fit in a tight space so I just stayed with the original type. Once the in-guard was repaired, I found a few other boards where the tantalums on the same rail also failed so don't be surprised if more start to fail. The 4708 service manual is here https://xdevs.com/doc/Datron/4708/DATRON-4708-CH-SH_c20030307.pdf It is now uploaded to KO4BB. The 4808 service manual will be very close since the 4708 and 4808 share similar designs. The 4708 uses a LTZ1000 as the reference instead of the array of zeners used in the 4000 and the lower spec'd 4700. You will have yourself a good calibrator once it is brought back into service. Be careful around the displays as there is hardly any room between the glass and front panel. Respectfully, Todd On Thu, Jul 20, 2017 at 12:55 PM, Fred <pa4...@gmail.com> wrote: Hi Tod, I just pulled that board (i think) and found a burned 22uF tantalum. Tantalum caps should have a very long life unless used on the wrong place. I guess this is an example. I do not even stock them, the last bad one I had to replace was in a G secutest 2 years ago. ( I repair around 10-20 Secutests a year and that was the only bad tantalum) With what type/value cap did you replace them ? I found the 4708 manual at KO4BB but that is a user manual without schematics. The calibrator should be OK but before I try to start her I always like check things like caps, connectors, solderjoints etc. It really looks like new, not even a scratch or dust. It came with a new looking HP8640 and a new looking HP counter 5248. Both from the same cal lab (part of a company that stayed there) that cal-lab closed about 30 years ago, but all gear stayed where it was (I already had received most of their gear a few years ago). This were the last things because my friend retires. Fred . On 07/20/2017 04:51 PM, Todd Micallef wrote: Fred, Shorted tantalums most likely. I had several on mine that went bad as quickly as I replaced them. I would start with the inguard supply board. I think the 4708 manual is available for download at KO4BB or xDevs. If not, I can dig up something. I have a set of the manuals. Todd On Thu, Jul 20, 2017 at 10:01 Fred <pa4...@gmail.com> wrote: Today a friend gave me a Datron 4700. It looks like new. It is stored (working) for many years in the cal lab he works. He was allowed to take it home (for me, in return I will repair his SA), He plugged it in, Fail 1 on the display followed by a sound and a smell. I opened it but nothing looks burned. I can not find a service manual, does someone has one ? On the back the label shows no options but if he remembers it well it should have all or at least most options. All slots are filled with pcb's. The "box" in the left upper corner is full and there is a very small pcb next to it. There is not much room left. Just enough to store a small multimeter between the huge transformer and that box. Fred www.pa4tim.nl ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/m ailman/listinfo/volt-nuts and follow the instructions there. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/m ailman/listinfo/volt-nuts and f
Re: [volt-nuts] Datron 4700 manual and options
Hi Todd, I will order a bunch en 35 or 50V. Replaced them for now with a smaller value I had. Is only a fixed value LM340 so not very critical. The data sheet states minimal 2u2 at the input and non at the output I found the 4707 manual and upto now the schematics are usable. Seems like I have the AC, ohm and current options. The board I can not find is the HV option. But I do not mind, I already have 3 calibrators that do have 1000V. I have a problem in the +/- 400V rails. They are +115 and -38V. I have no extenders but I use long flexible grabbers. (a wire with banana on one end and a grabber on the other. Lift the board, clip it to a testpoint, push the pcb in and measure. Not optimal but workable. First find out where the 400V is made. Thanks for the help. Fred On 07/21/2017 01:59 AM, Todd Micallef wrote: Fred, I used the same values and typically went up to the next higher voltage. I think most ended up as 35v since I bought them in quantity. Some people recommend the OS-CON family as replacements. Many of the failed tantalums fit in a tight space so I just stayed with the original type. Once the in-guard was repaired, I found a few other boards where the tantalums on the same rail also failed so don't be surprised if more start to fail. The 4708 service manual is here https://xdevs.com/doc/Datron/4708/DATRON-4708-CH-SH_c20030307.pdf It is now uploaded to KO4BB. The 4808 service manual will be very close since the 4708 and 4808 share similar designs. The 4708 uses a LTZ1000 as the reference instead of the array of zeners used in the 4000 and the lower spec'd 4700. You will have yourself a good calibrator once it is brought back into service. Be careful around the displays as there is hardly any room between the glass and front panel. Respectfully, Todd On Thu, Jul 20, 2017 at 12:55 PM, Fred <pa4...@gmail.com> wrote: Hi Tod, I just pulled that board (i think) and found a burned 22uF tantalum. Tantalum caps should have a very long life unless used on the wrong place. I guess this is an example. I do not even stock them, the last bad one I had to replace was in a G secutest 2 years ago. ( I repair around 10-20 Secutests a year and that was the only bad tantalum) With what type/value cap did you replace them ? I found the 4708 manual at KO4BB but that is a user manual without schematics. The calibrator should be OK but before I try to start her I always like check things like caps, connectors, solderjoints etc. It really looks like new, not even a scratch or dust. It came with a new looking HP8640 and a new looking HP counter 5248. Both from the same cal lab (part of a company that stayed there) that cal-lab closed about 30 years ago, but all gear stayed where it was (I already had received most of their gear a few years ago). This were the last things because my friend retires. Fred . On 07/20/2017 04:51 PM, Todd Micallef wrote: Fred, Shorted tantalums most likely. I had several on mine that went bad as quickly as I replaced them. I would start with the inguard supply board. I think the 4708 manual is available for download at KO4BB or xDevs. If not, I can dig up something. I have a set of the manuals. Todd On Thu, Jul 20, 2017 at 10:01 Fred <pa4...@gmail.com> wrote: Today a friend gave me a Datron 4700. It looks like new. It is stored (working) for many years in the cal lab he works. He was allowed to take it home (for me, in return I will repair his SA), He plugged it in, Fail 1 on the display followed by a sound and a smell. I opened it but nothing looks burned. I can not find a service manual, does someone has one ? On the back the label shows no options but if he remembers it well it should have all or at least most options. All slots are filled with pcb's. The "box" in the left upper corner is full and there is a very small pcb next to it. There is not much room left. Just enough to store a small multimeter between the huge transformer and that box. Fred www.pa4tim.nl ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/m ailman/listinfo/volt-nuts and follow the instructions there. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/m ailman/listinfo/volt-nuts and follow the instructions there. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin
Re: [volt-nuts] Datron 4700 manual and options
Hi Tod, I just pulled that board (i think) and found a burned 22uF tantalum. Tantalum caps should have a very long life unless used on the wrong place. I guess this is an example. I do not even stock them, the last bad one I had to replace was in a G secutest 2 years ago. ( I repair around 10-20 Secutests a year and that was the only bad tantalum) With what type/value cap did you replace them ? I found the 4708 manual at KO4BB but that is a user manual without schematics. The calibrator should be OK but before I try to start her I always like check things like caps, connectors, solderjoints etc. It really looks like new, not even a scratch or dust. It came with a new looking HP8640 and a new looking HP counter 5248. Both from the same cal lab (part of a company that stayed there) that cal-lab closed about 30 years ago, but all gear stayed where it was (I already had received most of their gear a few years ago). This were the last things because my friend retires. Fred . On 07/20/2017 04:51 PM, Todd Micallef wrote: Fred, Shorted tantalums most likely. I had several on mine that went bad as quickly as I replaced them. I would start with the inguard supply board. I think the 4708 manual is available for download at KO4BB or xDevs. If not, I can dig up something. I have a set of the manuals. Todd On Thu, Jul 20, 2017 at 10:01 Fred <pa4...@gmail.com> wrote: Today a friend gave me a Datron 4700. It looks like new. It is stored (working) for many years in the cal lab he works. He was allowed to take it home (for me, in return I will repair his SA), He plugged it in, Fail 1 on the display followed by a sound and a smell. I opened it but nothing looks burned. I can not find a service manual, does someone has one ? On the back the label shows no options but if he remembers it well it should have all or at least most options. All slots are filled with pcb's. The "box" in the left upper corner is full and there is a very small pcb next to it. There is not much room left. Just enough to store a small multimeter between the huge transformer and that box. Fred www.pa4tim.nl ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] Datron 4700 manual and options
Today a friend gave me a Datron 4700. It looks like new. It is stored (working) for many years in the cal lab he works. He was allowed to take it home (for me, in return I will repair his SA), He plugged it in, Fail 1 on the display followed by a sound and a smell. I opened it but nothing looks burned. I can not find a service manual, does someone has one ? On the back the label shows no options but if he remembers it well it should have all or at least most options. All slots are filled with pcb's. The "box" in the left upper corner is full and there is a very small pcb next to it. There is not much room left. Just enough to store a small multimeter between the huge transformer and that box. Fred www.pa4tim.nl ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] Solartron 7060G
A friend gave me a dead Solartron 7060G (TRMS version) It goes on with al segments and all leds on. A quick probing shows the -35V measures only -20V. I have not probes more rails after that. Does anyone has a service manual for this meter. Fred ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] 7061 mod
I added a heatsink and adjustable fanspeed control to my 7061. With the lid open at room temp 22 degrees the voltage meaured went up around 150 uV. In summer the meter get realy ot inside. In the test ( without cabinet around the pcb) the temp measured next to the ntc stayed 40 degrees plus/minus a half degree. Voltage readings also increased in stabiltity. http://www.pa4tim.nl/?p=2456 pictures are on the bottom of the page. Fred PA4TIM Op 19 sep. 2012 om 17:11 heeft Bob Smither smit...@c-c-i.com het volgende geschreven: The third volunteer to measure the TS has reported back his measurements and I have posted them on the project page: http://www.c-c-i.com/ts Thanks for the interest shown in this project! I have two more volunteers in line to test the TS and will get it mailed to the next one this week. A fellow volt-nut across the Atlantic has expressed interest, but we have not found an economical way to ship it. Best regards, smither.vcf ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] HP3457
Fabio, The manul states the inner temp can go up to 75 degrees, i measured over 50 so extra heating it looks not logical to me. It would be for sure more easy as cooling. Most important will be to get the temp stabel. A closet like joe suggested would be an option. You could let the front come out, that will give some temp leakage but an improvement. The meter produces enough heat to warm the closet and if you keep that temp at for instance 35 degrees all you need is a tempsensor and a fan ( with adjustable speed) . As long as the room temp stays onder 35 degrees there would not be a problem. I think I will try that. Replcing switches ect is not an option, no room. But instead of the rackmount ears I will mount to alu profiles and mount the current inputs, Reference input and bananabusses instead of the second input on the back. I make a small hole in the side to lead the wirer out. On the other side I mount a profile with a powerswitch and two bnc panel troughputs and cables to the trigger bncs. I opened the meter and followed the checks of chapter 4. First problem, I coul not find if i have pcb 3 or 13 and 5 or 15 40348C 70610503X D so i think it is 3 11134F 70610505Y F so i think it is 5 B11091 70610508X B is the clockboard The meter has a date stamp 1987 so i think it is 3 and 5 The PROMs have other numbers as stated , they are toshiba TC57-256D-25 the others are 2516-45JL from texas instruments and SP1 is closed and SP2 is open ( as for type 2764) Allmost al solder bridges that should be open are soldered, some i can not ind and some are there but not in the manual. All voltages ar within specs. Tested it with a variac like the manual tells. So this is good. But then i measured the clock voltage TP402 That is a bit low 2.7V instead of 3V (+/- 0,2) so i should adjust coil L401 but i can not find it. This meter is ex-belgium army, so it looks like it has some mods or is a very early model. So this makes adjusting everything a bit tricky. Thanks for the offer but the key I have more or less works. It is a bit frubbling but calibrating is not something I do every day and most times i leave the key just in the cal position. Fred PA4TIM Op 22 aug. 2012 om 09:58 heeft Fabio Eboli fabi...@quipo.it het volgende geschreven: Hello Fred, I'm certainly not expert here, but your idea of ovenizing the 7061 made me think aloud :) So here are some random toughts. My 7060 has no feet on underside and I noticed that the unit, zeroed on 10V sitting flat on its bottom, drifted badly if raised a pair of cm from the table, so the first consideration I can do is that the 7060 must be calibrated exactly in the same thermal equilibrium than in use. The 7061 is a different beast but the internals are not too much different from the 7060. The top and bottom covers are thick plastic covers, so they isolate a little the unit from the outside world but do not spread the heat around. The front and back panels are aluminium so probably if there is temperature difference between outside and inside, the gradient should be maximum near the panels. The infamous Fischer connectors (I hate them ;) should make a very good job at maintaining no gradient between connections of the leads, so thermocouple effects should be controlled well by these connectors, also if there is a strong gradient on the panel. Naturally this is just a guess from me, no mesurement involved, this is your speciality :) The last consideration is that if I would try to heat the 7061 I would try to avoid at any cost hot spots, so the heating should be spread on a large surface. As a first try I would place an aluminium plate on the underside of the instrument, in contact with the outer side of the plastic cover, and try to heat up this plate, for example bolting on or gluing transistors on it in a mesh pattern. As a second step I would try to isolate the heating plate from the outside with foam. Later I would check the meter behaviour and perhaps see what happens with another heat spreader-insulator on top cover. The problem is how to properly test it, you should have a sort of climatic chamber, in winter it's easier, just grab a pair of big enoug cartoons, one into the other and heat up the air between them :) Ok this is enough fantasy at work :) As for the key, I can duplicate mine and send it to you, if you want to try another key. Fabio. Fred Schneider pa4...@gmail.com ha scritto: So this is normal, hmm, my shop can be over 30 degrees when it is a hot summer and 15 degrees in a Cold winter so keeping it powered will not help in my case ( i am just an amateur voltnut so climatize my room is no option. But The service manual describes a test were you run it at 15 degrees, then at 38 degrees and then adjust diodecurrent until you get the best tempco. That would imply the thing should not react much on a few degrees. Would it be an option to ad tempcontrol
