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AVO METER USERS

John Peckham

Some time ago there was a thread on the topic of AVO meters which is now locked.

Shortly after my interest was re-energized and I started collecting AVOs again. 

I have been disposing of my collection following extensive counselling and aversion therapy but have slipped back and have purchased an AVO 8 MK 7 which was the last mark out of the Megger factory. I have had all the Marks of the AVO 8 but never a MK 6 or a 7 which I am waiting to receive.

I think it is a nostalgia thing from my youth  when I was starting out in amateur radio and always wanted one. At college early on we had a lesson on how to use an AVO which included selecting ranges and using the mirror scale. As a technician I was issued what the Post Office designated a "Meter Multi Range No. 12" . Later when promoted to a Technical Officer you were allowed to be issued with a Meter Multi Range 14C which was an AVO 8. Before the ink was dry on my appointment letter I ordered up my 14C  which was sort of badge of office.

I saw on the BBC programme "The Repair Shop" where their electrical expert re-furbishing a PO 12 meter and their leather expert re-furbishing the leather case. That sparked me in to buying one on Ebay to do the same as a memento of the past. I now have a 12D instrument which was made by AVO in the leather case. 

Has anyone else on this forum become an AVO collector or use one from time to time for its intended purpose? I used my MK 6 when doing some experiments where my Fluke DVM would not do due to it's high input impedance.,

Is there a support group for this minority group as I am off to an amateur radio show soon with a pocket full of cash and I fear I will be overcome with temptation if I see an AVO 8.

  • 0 in reply to ebee

    Yes, and the only reason for children to exist was to say nothing and act as the remote control ... and they only had to count to three to do that.

  • 0 in reply to Chris Pearson

    Oh yes that dot - was an icon. Even before icons existed. Thanks Chris, I had forgotten

  • 0 in reply to ebee

    I`m not going to mention those TV remotes that had a wire leading to the TV!

  • 0 in reply to ebee
    ebee said:
    I`m not going to mention those TV remotes that had a wire leading to the TV!

    Sorry, you already did. www.youtube.com/watch

  • 0

    I honestly don't know how many AVO 8's/7's I have, not because I have loads but because they're squirreled away in various places! I ought to find out, and check they're ok - and perhaps rehome them. I just picked them up because in each case it was either me taking them home or them going to the skip, which I can't cope with because of memories of my apprenticeship days when we were delighted to have use of a "real AVO".

    Which I guess answers the second question: no I never use them, I'll use one of my various DMMs for voltage etc readings and oscilloscopes for wiggly things. I can imagine using one to look at a ramping up/down voltage, but I've not felt the need. (I'm delighted to say I have a spare Fluke 8060, and one more which would be ok for parts at least, as they've been my "go to" meter for many many years.) 

    Of course the problem is the low impedance, to get around that I do have a VALVE AVO Meter CT38 if anyone would like it!!! Sadly needs a new meter unit, the one currently in there is the wrong one. Like in these links: https://www.opweb.de/english/company/AVO/CT38 https://www.vintage-radio.net/forum/showthread.php?t=156713 Seriously if anyone has a way of collecting it from near Plymouth (or I might be able to get it up to London) you're more than welcome to it!

    Cheers,

    Andy

  • 0

    Graham

    The AVO 8 MK 3 is the quintessential AVO. The last true AVO *, Bakelite case and built like a brick out house. The MK 3 replaced the MK 2 which had metal oxide rectifiers with the MK 3 having silicone.   A mint one with the leather case and original leads, clips and probes are now commanding a premium. 

    Chris

    I love the idea of keeping an old analogue AVO 8 to help keep the digital Fluke going.

    Zoom

    Kings Lynn Amateur Radio Society are having a rally on 7th of August at Gayton village hall. Loads of dealers and bring and buy stalls with all sorts of electrical kit on sale.  

    Turning a serviceable  AVO into a table lamp is a gross act of vandalism!

    My latest AVO 8 arrived in the post today (yes on a Sunday by Royal Mail). It is a MK 7 which was the last version out of the Megger factory.

    I also found a couple of MK 5s I forgot I had when looking for some AVO test leads.

    I have booked in to see professional help for my affliction! I am going to reduce my collection but will find it hard.

    Ahhh! Nostalgia aint what it used to be!

  • 0 in reply to ebee

    Yes, I had one of those. There was a shop not too far away that sold clapped out old tellies for 10 bob. One could usually keep them going for a while, but then what? Scrap it? Contrary to popular belief, one could render the CRT safe by whacking the gun off with a spade.

    (I couldn't possibly have afforded an AVO in those days.)

  • 0

    Hello Chris,

    The engine is a 12cc two cylinder four stoke petrol engine of my own design. It has been through several planned versions. Initially it had a 180° crankshaft and a constant depression (SU style) carb. I then converted it to a 360° (parallel) twin. The increased vibration made operation of the SU type carb difficult so I moved on to the final step of petrol injection. This was based on previous experiments on other engines.

    The 2mm bore metering pump uses helix spill control as in a full sized diesel. The working stroke is around 0.2 mm. It is driven from the crankshaft so it injects on each induction stoke. The injector is of the poppet (mushroom) type with a bore of 1.4mm. I have previously experimented with more conventional needle type injectors with nozzles down to 0.2mm but these were not very successful due to leakage past the needle.

    Ignition is by conventional points, coil and distributor and the engine is connected to a permanent magnet motor which is used as a starter motor and a load. I run it on Alkylate fuel as this smells much less than pump petrol. It costs more but as a five litre can lasts me several years it’s not a real problem (it also doesn’t ‘go off’ like pump petrol).

    There are various picture of this and other engines on Flickr:

    https://www.flickr.com/photos/153503473@N05/

    The video clip here shows some brief load trials. As the resistor bank I am using is 1 ohm when all are switched in I am just measuring the current. It will achieve around 9A so 81W but my key requirement is that it can cope with load changes as I intend to build a small tractor around it one day.

    https://youtu.be/7RVp_fwLo0o

    I am using an analogue meter, but not an AVO as it takes up too much space ;-) 

  • 0 in reply to Roger B

    Roger, thank you. Most impressive!

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