Ancient Meter Questions - Page 1
Forum section: electronics / testgear

author: mentaldemise
author_rank: Regular Contributor
timestamp: July 12, 2015, 09:32:30 pm
content: Hey guys. I just got this meter, my first analog! I'm wondering if there is anything to the effect of calibration for it.I had to re-solder a power wire onto it, and that was about it. 5VDC measuring seems to not work but the others do. Is this just a matter of find-the-dead-resistor to fix?Also, anyone know anything about it? It has "RVAH-12 RADIO" on the back which would be hard to see:Thanks!

author: retrolefty
author_rank: Super Contributor
timestamp: July 12, 2015, 10:27:29 pm
content: Looks like maybe a military version of the Simpson 260? The needle zero looks ok. Check it's internal batteries. Pretty worn but if it is a Simpson they were known for pretty long life. Heck I've got a 40 year old one in the garage somewhere.

author: mentaldemise
author_rank: Regular Contributor
timestamp: July 12, 2015, 10:58:20 pm
content: Any idea which marking is the date? I thought8183 when I got it. But then I'm reading it's 50s-60s.

author: Unknown
author_rank: Unknown
timestamp: July 13, 2015, 12:55:30 am
content: Made by Simpson for the US military. My father had one, either picked up during his apprenticeship here in Aus or that fell off the back of a truck (& into his pocket) when he was a Nasho. There were several versions made with much the same case but different internals from, I think, the 50's right up till the 80s. Don't think there was an exact civilian equivalent.I used to have a site bookmarked where some of these supplier & contract codes could be looked up, but it went down years ago & I deleted it. Maybe try the US GAO? But it's pretty straightforward - MFR 08311 specifies the manufacturer/plant/location, NObsr-87234 is the contract number (Naval Office, Bureau of Ships, contract # 87243), and A3258 is the serial/supply #.One big problem is that most of them used a 22.5V battery (a 505A, I think) which can be difficult & expensive to get these days...

author: mentaldemise
author_rank: Regular Contributor
timestamp: July 13, 2015, 12:58:12 am
content: Thanks for the info!You are correct about the 22.5 Axial leaded battery(looks like a 9V form factor but plus is on the opposite end of negative)! It's still in there and charged. Well, 21V still from my measurement!

author: tautech
author_rank: Super Contributor
timestamp: July 13, 2015, 01:00:56 am
content: Quote from: Tac Eht Xilef on July 13, 2015, 12:55:30 amSame with old AVOs, but a homemade stack of 3V button cells will get around that problem.

author: tautech
author_rank: Super Contributor
timestamp: July 13, 2015, 01:08:19 am
content: Quote from: mentaldemise on July 13, 2015, 12:58:12 amCheck it with a moving coil meter or with a small load if using a DMM for a true voltage reading.

author: Fungus
author_rank: Super Contributor
timestamp: July 13, 2015, 11:11:58 am
content: Yes, there's usually a trim pot in there somewhere. Don't expect to get it very accurate on all scales though.Those meters place a load on the thing being measured (enough to push a needle against a spring!).The load is usually printed on somewhere on the meter, you may have to compensate for the effect in your calculations.

author: -jeffB
author_rank: Regular Contributor
timestamp: July 13, 2015, 04:18:37 pm
content: Quote from: Fungus on July 13, 2015, 11:11:58 amIt's right there on the lower right of the meter face, under the right needle stop. I can't make out the first digit -- looks like 20000 ohm/V or 50000 ohm/V to me.