Avominor type HR (DC Only)

[The Philpott]

(No, i haven't got one..) But see archive.org/stream/airforcelistmay1941grea

The more digging around that i do the more convinced i am that the HR Avominor and the Low Resistance Ohmmeter were all (or almost all) supplied direct to the military. Having been overstamped 'cancelled' from 1939 ads./catalogues, they then earn a mention in an ad in 'The Air Force List, May 1941'. This booklet, which was issued two times a year, is fundamentally a staff list for high and medium echelons of the RAF! The cover is marked 'This book is the property of HM Government and is to be kept in safe custody by the person to whom it is issued'- certainly something we would not have wanted to land in Haw-Haw's lap.

The first few pages are devoted to ads for largely air force specific products and services-
everything from barrage balloons to anodising to jubilee clips to air cooled donkey engines to dunlop a/c tyres. (and of course tobacco) I have good reason to believe that the AVO ad was up-to-date at the time of publishing and would not have included items which the company could not supply fairly quickly- so i think that all these little meters went to the military, the minors to secretive radio/radar testing establishments and the LRO most likely to the RAF/Fleet Air Arm.

Well this is my theory anyway; i would not expect any to turn up now and fear that some ditching/burning/burying/dumping will have occurred in the time honoured military fashion that we try to understand. One just hopes that some sticky fingers may have been in the right place at the right time.

Dave Philpott

[micheal]

Hi Dave i have managed to collect two over the last few years one in it's original
box with leads. Serial No 404-79 (July 1939) and (206-108 (Oct 1938)

[The Philpott]

Aha! Would you be able to contribute photos at all? Richards Radios in particular would be very pleased to include some data and pictures on this. Also pmmunro (on here) is researching such things currently.

Thankyou for giving the serial numbers as such things dispel the fog a little on the extent of the production run. Do they have any military marks?

.... And WELL DONE by the way. (Double well done if they actually work)

[tis your junk]

If you mean one of these my father had an example which he always told me he had brought pre-war to repair his TV.

He did later serve in the RAF but curiously not in the electronic/electrical trades.

TYJ

[The Philpott]

Mega, thanks for that! Questions-

1.Could you advise the serial number at the lower end of the scale?
2. Do you mind me donating the image to archive?
3. Will you be able to get some hi-def images in due course?

...And if you're using Dibnah quotes you must be one of the good guys..!

[micheal]

Sorry Dave i do not have the facilities to take pictures, but mine is just like the one posted by TY.

[The Philpott]

No problem, thanks for replying! Should you (in the future) want to do any pictures of rarities Private Message me and i am sure we can come to an arrangement.

Regards
Dave

[micheal]

Thanks Dave, i forgot to mention that it has no military markings on meter or case. The large compartment to the right of meter is for the rather thick leads same diameter AVO 8 leads rather heavy for wander plugs.
Regards Mike

[The Philpott]

Yes, i know those leads, my Type E came with a pair. One perished, one completely ok. Possibly something to do with the pigment used, or they could have been from two different sets. The clip/prod sockets are threaded, (not push-in type)

[tis your junk]

Dave,

I like to think I'm one of the good guys.

However it is not that simple for me to say yes to any of your questions right now.

Perhaps at Christmas I'll can do something.

Although they are not shown in that picture there were a set of leads which had banana plugs at both ends. Although it now seems shocking ( sorry could not resist) the hot end had uninsulated "crocodile clips". I seem to recall they had reacted very badly to light and had disintegrated somewhat.

Like Mike I don't remember any arrow head marks or military makings of any kind, which kind of confirms the family legend.

Sorry I can't help any more right now.

TYJ

[The Philpott]

Yep, No CAT I,II,III in those days, it was very much incumbent on the operator to ensure he did not get electrocuted. The croc clips were interchangeable with alternative insulated long prods, but if these were not included as standard in the kit the company would not have been thought to be negligent- just the way it was..

Thanks for confirming no military marks. That is a very special acquisition or inheritance and although rarity doesn't imply quality it has both attributes.

[The Philpott]

Some thoughts- some confirmed, some surmised-

The 50uA facility must go straight across the swamp and movement and is not marked on the front so + must go through the ctr. of the ohms zero knob.

Resistance facility is not self contained so the onboard battery will have been deleted and the space gained filled with medium size resistors (with or without carbon trimmers) and there will be a bobbins for 250uA, 2.5v and (probably) 10v ranges. The metal rear cover may be a one-piece full size affair but still have 6 screws not 4. (Two of them will be miniature screws holding down top-hat washers, and if undisturbed at least one will be packed with black composition bearing the factory seal.)

Quite hard to see, but 1 Megohm appears to be centre scale on the low range (resolution down to 50kohm), which becomes 10 Megohms on the high range (res 0.5Megohm)

The V and uA scale is uncluttered, and is on a fairly linear 100/25 basis.

The deletion of the battery compartment will have decreased the destruction/disposal rate, so there could be more- aided by the box which was provided, it seems, as standard equipment. The wise will have removed the rotting test leads from the box as i can imagine sticky residue would stick to the blue liner quite well.
OK, some will have been abused, dropped, casually thrown away or played with by kids over the years, but hopefully not too many

[The Philpott]

-- Incidentally, safely provisioning 100volts or thereabouts for (eg) establishing the 50Megohm range works, would be viable; a stack of cheapie alkaline button cells in a tube, rocket launching tubes (eg bright star) tend to be the right bore for AG10/12/13.

(Your best ever excuse for buying fireworks in adulthood..)