Rules and Guidelines
Want to participate in the discussions? Please read our Community Rules and Guidelines. Need some help? Visit Support and Answers.

  • State Not Answered
  • Locked Locked
  • Replies 19 replies
  • Subscribers 40 subscribers
  • Views 3393 views
  • Users 0 members are here
Options
You may also be interested in
This discussion is locked.
You cannot post a reply to this discussion. If you have a question start a new discussion

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.

Parents
  • 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!

Reply Children
No Data

Join us to get the best from IET EngX.

Joining EngX lets you personalise your experience so you stay up to date on the topics that interest you, plus you’ll be able to make connections who are looking to collaborate, exchange ideas and more.

Join us Not now

Community Rules & Guidelines