General Radio 1454-A - Page 1
Forum section: electronics / general

author: jonpaul
author_rank: Super Contributor
timestamp: February 24, 2021, 01:00:36 pm
content: Hello all:Unearthed GenRad 1454-A 10,000 ohm voltage divider. Serial 1973.Use will be to calibrate meters with a 10.0000 V standard reference, use as a potentiometer or voltage divider up to 100V.Does SN 1973 come before or after the accuracy improvements implemented per the Gen Rad experimenter article of Volume 33 No. 7, July, 1959. ?Can you say the date /year of mfg?The articles mention selection of certain resistors to provide the improved specs?It works OK but several switch taps are slightly flaky, and not stable.How to open the chassis and clean the switch contact?Many thanksJon

author: chekhov
author_rank: Regular Contributor
timestamp: February 24, 2021, 02:36:21 pm
content: Hi,Maybe some photo will help people to answer certain questions ?Doesn't it have screws under knobs ?

author: jonpaul
author_rank: Super Contributor
timestamp: February 24, 2021, 03:05:09 pm
content: Hello all:I succeeded to open the unit, the foot screws are in long standoffs from front panel. very easy.Spechttps://www.ietlabs.com/pdf/Manuals/GR/1454-A,%20-AH%20Decade%20Voltage%20Dividers.pdfapp notes see page 13 and uphttps://www.ietlabs.com/pdf/GR_Experimenters/1959/GenRad_Experimenter_July_1959.pdfInside its pristine, and the contacts seem bright and still have the original lube.I used Miller Stephenson MS-230 contact cleaner, then exercised ever decade.Now it works 100%, Testing on a Fluke 8842A DVM and with HP 4115A precision Power supply set a 10.0000V all decades seem to be well within spec.As the app note was 1959, and this unit seems much later (by the knob style and case condition) I think its the revised version.Any other Metrology Mavens or GR 1454 owners advise on lube or serial numbers vs mfg year is appreciated.Many thanks Jon

author: jonpaul
author_rank: Super Contributor
timestamp: February 24, 2021, 03:33:06 pm
content: Here are A few photos, need recommendations on contact lube and cleaner for gray crinkle case and front panel, case has paint on it front has stickers residue.Many thanks againJon

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: February 24, 2021, 06:24:01 pm
content: Can't tell you much about accuracy, but it will degrade if you load it down. I clean the contacts and use Superlube grease or Vaseline. Remember the center contact! Properly cleaning these up can be a bit of a project. These are a nice general purpose divider but remember, they're no Fluke or Julie or ESR.

author: jonpaul
author_rank: Super Contributor
timestamp: February 24, 2021, 07:02:01 pm
content: Conrad many thanks the GR spec is fine for my use.In 1965..1967 I worked for Loebe JULIE in NYC, as a work-study tech while at college.I managed to save a few of their handwound resistors, but alas not the real standards.Jon

author: bob91343
author_rank: Super Contributor
timestamp: February 24, 2021, 09:57:36 pm
content: I would avoid lubrication unless there is a problem.

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: February 25, 2021, 01:05:50 am
content: Quote from: bob91343 on February 24, 2021, 09:57:36 pmReally? There's a lot of pressure on those contacts and the factory certainly lubed 'em.

author: Kosmic
author_rank: Super Contributor
timestamp: February 25, 2021, 01:37:30 am
content: Personally I had to clean and lubricate all the old decade resistors and KVD I bought. Probably the reason they were sold in the first place.Anyway, I clean with IPA, then apply Deoxit G5 on the contacts (don't spray all over the place. Use something like a syringe). Finally I lubricate the contacts and switchs with Deoxit S5.They all came out of that little process good as new.

author: Stray Electron
author_rank: Super Contributor
timestamp: February 25, 2021, 02:25:57 am
content: Quote from: Conrad Hoffman on February 25, 2021, 01:05:50 amI would take what Conrad says asgospel!IMO not putting lubricant on any sliding metal surfaces is just asking for problems.

author: srb1954
author_rank: Super Contributor
timestamp: February 25, 2021, 09:53:07 am
content: Quote from: jonpaul on February 24, 2021, 03:33:06 pmNice clean condition. I have S/No 1987 so it may have come out of the same production batch as yours.However mine is not as original looking as yours: someone had removed the original GR binding posts and replaced them with non-standard binding posts although they did use some nice gold-plated ones.

author: jonpaul
author_rank: Super Contributor
timestamp: February 25, 2021, 10:24:00 am
content: Rebonjour a tous!Many thanks for the notes, it was from a ham radio flea (SV ARRL) or a silent key friend's estate. Very little use.1/ After contact cleaning and exercise, Divider is working 100%, in all switch pos.2/ I used MS-230 contact cleaner, original lube is still present on all switches.3/ The ratios are within or better than spec, tested with Fluke 8842A.4/ The crinkle finish is quite pleasing, Used IPA, then paint thinner and finally acetone of the paint of the case,impossible to remove the huge paint stencils without affecting the finish. Any other things to try?Many thanks again.Jon

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: February 25, 2021, 02:14:12 pm
content: GR black and grey crackle finishes are quite fragile and almost anything will dull or damage them, even Windex! I've had some luck with the yellow markings using brief and repeated applications of naphtha or xylene, operative word being brief. Sometimes I just live with the yellow markings because they can just be too tough to get off. A good polishing with Armor-All will bring back the shine.Caution- I'm wrong only slightly less than I'm right, and that's on a good day!

author: SilverSolder
author_rank: Super Contributor
timestamp: February 25, 2021, 02:29:03 pm
content: Quote from: Kosmic on February 25, 2021, 01:37:30 amThat's exactly what I do, and the results appear to be good and durable.

author: SilverSolder
author_rank: Super Contributor
timestamp: February 25, 2021, 02:34:23 pm
content: I have an example of the 1454-AH model, which is the same as yours except 100K Ohm resistance instead of 10K.I measured mine with a ratio transformer (<1ppm accuracy) and found it to be well within spec (most positions/setting are 10x better than spec!).But the real winner is: it is extremely stable, so once you know what each setting actually is, that is what you will get - every time. That fact makes it usable for a lot of things. The sheer physical size of everything inside means self heating at modern voltages (10V or less) is not a big concern.

author: jonpaul
author_rank: Super Contributor
timestamp: February 25, 2021, 03:05:50 pm
content: Conrad, many thanks re the gray crinkly finish, thought so!I will test with xylene later.Still the front panel cleaned up well, just traces of stickers.Jon

author: Kosmic
author_rank: Super Contributor
timestamp: February 25, 2021, 04:13:08 pm
content: Quote from: SilverSolder on February 25, 2021, 02:29:03 pmYep, Deoxit for the win!

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: February 25, 2021, 05:56:34 pm
content: Quote from: jonpaul on February 25, 2021, 03:05:50 pmBe very careful as xylene will definitely attack the paint.

author: guenthert
author_rank: Frequent Contributor
timestamp: February 25, 2021, 06:00:04 pm
content: Quote from: Stray Electron on February 25, 2021, 02:25:57 amI know next to nothing about materials, but afaik, if at least one of those metals were brass (which I don't know whether it is), then additional lubrication wouldn't be necessary (and probably not advisable). Isn't brass advertised as "self-lubricating"?

author: Kosmic
author_rank: Super Contributor
timestamp: February 25, 2021, 06:02:54 pm
content: Quote from: jonpaul on February 25, 2021, 10:24:00 amyou could try magic erasers. They don't last but they work really well.https://www.mrclean.com/en-us/shop-products/magic-erasers

author: bob91343
author_rank: Super Contributor
timestamp: February 25, 2021, 08:54:08 pm
content: I recently acquired two GR decade resistors of similar type. Apparently they have had so little use that the contacts were a bit unstable. But after some use, they have come back well within spec, even after most of a century since manufacture.As far as I know, the contacts have never been lubricated since first sold. Perhaps if they get used a lot there will be some contact wear but these are beefy contacts and won't wear out within my lifetime. But then, I am old.Lubricants vary in their activity. They can cause poor contact because they don't conduct current. It's not wear we are worried about; it's accuracy. And some may cause long term damage due to chemical reaction.

author: stevebyan
author_rank: Contributor
timestamp: May 25, 2021, 11:34:30 am
content: Quote from: Conrad Hoffman on February 24, 2021, 06:24:01 pmHow do you get in to clean and lube the center (wiper) contact? On the General Radio switches that I’ve seen, it’s swaged together. I don’t see how to clean it or get fresh grease into it.

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: May 25, 2021, 09:28:27 pm
content: There's usually some wavy contact washer in there. Usually you can squirt it with contact cleaner, then jam a bit of grease in after it's dry. Deoxit Faderlube might also be a good choice for the center, but it's light oil, not a grease. The big pots in the bridges are another place where the center contact can give trouble. You'd think grease could lift contacts and cause poor connections, but it turns out to be really hard to do. If you have some time to burn, go to the Nye site and look at their info on electrical contact lubes. I have it from someone that used to work at L&N that Vasoline was the recommended lube for the big lug type switches. I don't know what General Radio used, but it tended to turn green (if it didn't start that way) and by now is ready for removal and replacement with something better.

author: stevebyan
author_rank: Contributor
timestamp: May 26, 2021, 02:47:44 am
content: It's been a while since I opened it up, but I couldn't see any opening big enough to force lubrication into the wiper bearing on the switches from my G-R 602-J resistance decade box.The zero resistance is a little above spec. I suspect the rotating contacts in these wipers are the problem.

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: May 26, 2021, 01:28:29 pm
content: Well, hypo needle and lots of pressure at the interface, plus a certain amount of faith that something probably got in there.

author: SilverSolder
author_rank: Super Contributor
timestamp: May 26, 2021, 01:45:01 pm
content: I found the DeOxit Shield product lubricates well enough to make the Genrad operate smoothly, without the risk of anything "bad" getting on the contacts - since I put it on the contacts too, in the first place!It seeps in through the tiniest gaps.https://caig.com/product/deoxit-shield-sn5s-6n/