Teardown:Julie Reasearch Labs VDR106 KVD - Page 1
Forum section: electronics / general

author: Pipelie
author_rank: Regular Contributor
timestamp: January 01, 2017, 08:24:48 am
content: another Kelvin-Varley Voltage Divider come from Julie Research, I opened up this beast for the first time and was surprised to find that this divider appears to have no adjustable component.SpecificationsResolution :0.1 ppmAccuracy: 1 ppmStability: 1 ppm/yearhttp://www.ko4bb.com/getsimple/index.php?id=download&file=06_Misc_Test_Equipment/Julie_Reasearch_Labs_VDR1067_VDR307_Kelvin_Varley_Voltage_Divider_Operator_Manual.pdf

author: Pipelie
author_rank: Regular Contributor
timestamp: January 01, 2017, 08:28:16 am
content: more pictures

author: Pipelie
author_rank: Regular Contributor
timestamp: January 01, 2017, 08:32:25 am
content: switches

author: Pipelie
author_rank: Regular Contributor
timestamp: January 01, 2017, 08:35:55 am
content: sealed resistors,can't find any information about this resistors.if anybody want to see more detail about this KVD, please let me known , I'll take more pictures and upload.

author: lowimpedance
author_rank: Super Contributor
timestamp: January 01, 2017, 09:51:05 am
content: Some serious point to point there. And interesting note in the manual under the maintenance section "that if the ratio is far of from its proper value a visual inspection may reveal short circuits of the busbars" and "gentle bending is permissible"..... indeed.,The black sleeved connections look interesting.Thanks for the pics.

author: VintageNut
author_rank: Frequent Contributor
timestamp: January 01, 2017, 10:14:27 am
content: It looks like the first three decades are "special", sealed box, probably oil filled. The black sleeve wires may be tweaking to match the resistors. The black sleeve wires appear to be an "amateur" job.You will require a very tight tolerance divider to check the goodness of the first decade.

author: Robert763
author_rank: Super Contributor
timestamp: January 01, 2017, 10:22:53 am
content: Hi,Thanks for posting the pictures. I have one of these (donated th manual to KO4BB) but have never opened it. The resistors were made by Julie as were the switches. The rights were bought out by Ohm-Labhttp://www.ohm-lab.com/index.htmlwho still make the high voltage dividers (and resistors to order). A websearch will bring up some of the Julie patents. No adjustments. Fine tuning appears to have been via the sleeved links of small gauge wire. Note the intermediate twist and solder joints for thermal EMF cancellation. These were national lab standard dividers in their day and still perform well. The NIST accepted check proceedure is included in th manual. The red "glyptal" enamal on the solder joints indicate that they have not been touched. The "amateurish" appearance is probably due to difficultly in adjustment.

author: manganin
author_rank: Regular Contributor
timestamp: January 01, 2017, 10:57:06 am
content: The black covered wires are Manganin and used to fine tune the divider after sealing.Quote from: Pipelie on January 01, 2017, 08:35:55 amThe metal boxes are actually their DMR series decade resistors, without painting and thumb nuts replaced with oridinary nuts. Please see the data attached.Oil filled but not hermetic. Ceramic insulators with simple rubber seals.

author: Vgkid
author_rank: Super Contributor
timestamp: January 01, 2017, 11:16:03 am
content: That is truely gorgeous on the inside. As manganin pointed out, those black wires are the trims. You can easily tell by noticing the extra wire sticking out.

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: January 01, 2017, 05:20:07 pm
content: I have serial number 1 of VDR 307 that I bought from JRL some years ago. I like to think the late Loebe Julie himself had a hand in tweaking it, though I've no idea. It's entirely discrete resistors with manganin trims. It's a 5' rack panel, rather than the narrow ones used on the later units. Haven't had it off the shelf in a while, but I think every tap of the main divider was brought out to banana jacks on the rear panel, or something similar.Remember, Loebe Julie had a lot to do with what we consider the modern opamp-http://electronicdesign.com/analog/whats-all-julie-stuff-anyhow

author: Vgkid
author_rank: Super Contributor
timestamp: January 01, 2017, 07:40:22 pm
content: Those switches are made by Sprague. Yes, the capacitor company.

author: Pipelie
author_rank: Regular Contributor
timestamp: January 02, 2017, 07:09:46 am
content: Thank you all, guys.looks like That is not an easy task to trim the resistor.I'll put it in test after Chinese New year holiday.I uploaded the high resolution pictures to FTP, in case of someone zoom in for more detail.Here is,https://xdevs.com/doc/Julie_Reasearch_Labs_VDR1067_VDR307_Kelvin_Varley_Voltage_Divider/Find some pictures of DMR-105-10K from eBay, attached.

author: niner_007
author_rank: Frequent Contributor
timestamp: June 19, 2020, 01:03:06 am
content: I have the sickness. I scored one of these too :-)

author: Robert763
author_rank: Super Contributor
timestamp: June 20, 2020, 07:04:57 pm
content: Now you need 3 voltage feferences, another divider, a differential voltmeter a 7 or 8 digit DVM...Welcome to volt nuttery, now about time and frequency

author: niner_007
author_rank: Frequent Contributor
timestamp: June 20, 2020, 09:20:04 pm
content: Quote from: Robert763 on June 20, 2020, 07:04:57 pmExcept for the references, I have more than 3 of everythingI’m working on having few 24/7 references running, with backup batteries etc.