What should I do with my old AVOmeter? - Page 1
Forum section: electronics / testgear

author: Brumby
author_rank: Unknown
timestamp: January 25, 2016, 05:22:25 am
content: I've worked out it's a Model 8 Mk II, manufactured September 1959.Needs a good clean, including removal of some crusty green stuff in the battery compartment and there is a crack in the case. It has a label on top:Australian AgentsElectrical EquipmentOf Australia Ltd---- 75 Liverpool St. Sydney ----The meter doesn't read accurately - out by 30% or so on DC volts and about 98% low on DC amps. But I've found a circuit diagram, so I might have a go at troubleshooting it.It has a leather carry handle that's in petty good nick and comes in a brown 'solid cowhide' carrying case that is reasonable, except for the buckle straps that are showing their age.It's never likely to feature as a functional unit on my work bench - so what could I do with it?

author: tautech
author_rank: Super Contributor
timestamp: January 25, 2016, 05:27:11 am
content: Fix it, if only for the 2.5 kV range you might rarely need.I've got a few AVO's just for that reason.

author: Brumby
author_rank: Unknown
timestamp: January 25, 2016, 06:24:45 am
content: That was the one thing that stood out to me as well. The possibility of that is pretty low - but you never say 'Never', do you?

author: tautech
author_rank: Super Contributor
timestamp: January 25, 2016, 06:34:56 am
content: Quote from: Brumby on January 25, 2016, 06:24:45 amMy best one is a Avometer 8 with a 3 kV range like this one:

author: rqsall
author_rank: Regular Contributor
timestamp: January 25, 2016, 11:27:43 am
content: Quote from: tautech on January 25, 2016, 05:27:11 amWhen you use an AVO on HV circuits you need to be aware that it's impedance is way too low for measurements on say CRT circuits. The meter will load the circuit down as if it's nothing.I have an AVO (inherited), but I never use it.

author: Orange
author_rank: Frequent Contributor
timestamp: January 25, 2016, 08:22:40 pm
content: The meter comes from the tube era. Perfectly usable for tube equipment repair

author: joeqsmith
author_rank: Super Contributor
timestamp: January 26, 2016, 01:02:15 pm
content: Good looking antique. I would just hang onto it. You may want that meter movement some day.

author: Ian.M
author_rank: Super Contributor
timestamp: January 26, 2016, 01:12:12 pm
content: You wont find a better mass produced analog meter movement. Yes there are specialist movements that are superior, but they have niche applications and cost an arm and a leg. *EVEYBODY* should have one good analog meter - for when you have suspicions that your DMMs are lying to you due to fast transients etc.

author: Kleinstein
author_rank: Super Contributor
timestamp: January 26, 2016, 01:43:58 pm
content: Analog meters can give wrong readings too, if higher frequency signals are present. I remember my old analog meter showing about 80% of full scale in essentially all ranges (3 V ... 1200 V) when a 50 KHz 5 V square wave (e.g. CMOS output) is prensent.For just a small error I would not do anything about it. It probably better to have it in original state than fixed up with a few new bodge resistors. The analog meter is not the right choise if you need a accurate reading anyway. Cleaning the corrosion from the leaking battery is of cause a good idea.

author: ozwolf
author_rank: Regular Contributor
timestamp: January 26, 2016, 01:51:56 pm
content: Analog meter clock? If I could get three of the same model at a reasonable price, that's what I'd do.CPU usage gauge?Perhaps even just hang it on the wall as a piece of art.Ozwolf

author: oldway
author_rank: Super Contributor
timestamp: January 26, 2016, 02:15:20 pm
content: I have had several Avometers, model 7 and 8.I still have a model 8 mark IV and a model 8 mark VI.There is no doubt about it, the model 8 mark IV is the best of all.(see pictures)The best quality, the best technology, the best components.Model 8 mark VI is crap. Nothing to do with the mark IV.http://www.richardsradios.co.uk/avo8.html

author: oldway
author_rank: Super Contributor
timestamp: January 26, 2016, 02:17:45 pm
content: Some more pictures:

author: MrSlack
author_rank: Frequent Contributor
timestamp: January 26, 2016, 02:22:31 pm
content: Nice teardown photos.I had an Avo years ago for HV stuff. I now have a bic biro with an old probe tip on it and lots of 10M and a final 10k resistors in series as a voltage divider all filled with epoxy. Far more compact. Good for up to 7kv so far