Admirable AVO

Awsome.
Very nice way to start the day !

Over on the vintage radio forum are AVO experts who are usually keen to acquire serial numbers and data for the register.

I still have the Model 8 Mk.II that dad gave me, worn and damaged in places but still fully functional. I don't use it any more, I have a couple of later ones that were maintained in calibration until the 1990s that don't have any sentimental value. It's useful to have a couple of moving-coil meters on hand when working on machines, and I keep a set of shunts in the drawer although they don't come out often.

Doors are closing behind us for maintaining moving-coil instrument because the skills and tooling to service the movements are in very short supply now. The AVO Valve Characteristic Meter is a case in point, as it uses a very sensitive (30μA FSD) movement, even more sensitive than the multimeter. The last company that would repair and calibrate them have stopped offering the service and the chap who had the experience and knowledge is no longer alive, so now we're on our own. It can be worked around by using a more modern movement and a buffer circuit that matches the original sensitivity and resistance, but the machines themselves are valuable and more so with the original meter in place. There is a pair of protection diodes to hopefully save the coil from destruction if the controls are set wrongly but they can't protect against 100% of all possible mishaps.

It focuses the mind when dialling in the settings.

Testing audio valves on the dining room table, a while back:

Lucien: you must have a very understanding wife or you live alone.

This is specifically the dining table at the family home which is a bit more flexible re. comings and going of electrical apparatus. The room at that time contained a working resistance dimmerboard for the lighting, a mercury arc rectifier, an Aeolian roll-playing Orchestrelle, six models of Goblin Teasmade, various cameras and projectors, even an AVO meter or two.

You do live alone or your wife has simply given up - wise woman.

Messages overlapped.

I have a couple of old Evershed and Vignioles constant pressure/insulation testers. Iwas also toying with reconditioning them but was struggling to find suitably skilled people and suitable components so I ended up leaving them as they are.

Marvo- If ever you are stuck for a place to store them..........

I have one from about 1908, not that long after they coined the 'Megger' name, that is still usably within calibration. I think the voltage is a slighly low on account of the generator losing magnetism but really not very much, and it's within cal for the actual resistance reading. The magnet could be re-charged to bring it fully back in-spec but as it is still sealed with a proper lead seal, I don't want to open it.

You do live alone or your wife has simply given up - wise woman.

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We're not married, but in any case this pic is an old one, taken before we met.

I admire your dedication to preserving old electrical artefacts and equally the technological knowledge associated with them.

Thought: could you do the same with telectrix and Pete999? ?

marconi said:

I admire your dedication to preserving old electrical artefacts and equally the technological knowledge associated with them.

Thought: could you do the same with telectrix and Pete999? ?

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no bloody chance. he'd have us pickled in brine and put on display in his museum.

He can’t be living alone, or those curtains would be his choice.