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Old 8th Apr 2020, 8:42 pm   #1
Nixie tube
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Default AVO 9sx Panclimatic High sensitivity

Hi everyone,
I have just registered on this forum so please be patient if I post in the wrong place etc:
I am currently in process of repairing an AVO 9sx for an elderly gentleman who would love to see this item working again.
This is a 'Number 1 Test Set NATO Issue Panclimatic High sensitivity model.
However the movement coil itself is open circuit (hair springs and swamp bobbin OK) and I am seeking either a donor AVO Meter to 'rob' or a complete working movement itself, as repair of the movement itself is not a feasible option.
Could anyone possibly help?
If not, any advice as to which other AVO models shared this particular movement would be appreciated
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Old 8th Apr 2020, 10:33 pm   #2
The Philpott
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Default Re: AVO 9sx Panclimatic High sensitivity

Hello there. There's little doubt that you're looking at a meter movement transplant...rather than risking stripping a donor movement down!

Avometer Model 9 MkII movement is compatible.
Realistically this is your only choice as the Model 8 (early) and Model 8 MkII/MkIII movements MAY be compatible but .. the problem with them is the scale plate is designed on a 100/25 basis so will be useless for the 100/30 meter. You don't really want to be swapping scale plates around as 1) it's very easy to damage the needle and 2) there is a number hidden at the bottom of the scale plate which denotes the scale shape/arc. If these don't match then a scale plate swap with any sort of accuracy- and good alignment- is not possible.

The Nato test set you are dealing with has features on it's scale plate that are different from the standard Model 9 MkII item- your customer may have to tolerate a 'normal' scale plate without the special text.

I hope this makes sense; you can 'phone me to clarify if that would help.

Dave
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Old 8th Apr 2020, 11:42 pm   #3
Techman
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Default Re: AVO 9sx Panclimatic High sensitivity

Unfortunately I've got bad news.

Virtually every other one of this model of AVO has an open circuit movement. The stock of replacement movements was used up many years ago and you're right at the back of a long line of people looking for this very movement. Even if you were lucky enough to find one, it would just go the same way in the end - it's a 'stock fault' with them and they're well known for it.

Trying to fit another movement is basically as Dave describes above. It's a shame really, as some of these meters are in mint condition, but to be brutally honest the meter is scrap, so don't waste your time on it - been there, done that with one years ago!
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Old 9th Apr 2020, 8:22 am   #4
The Philpott
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Default Re: AVO 9sx Panclimatic High sensitivity

Opinions vary but i would say no need to scrap it- it may just have to have the 'lid' put back on and shelved until and unless a donor meter comes along. Once dust gets in it's impossible to get it all out again.

If anything prices are in a slight slump, and Model 9 MkII typically fetches slightly less money than Model 8 MkIII. There are, paradoxically, less of them around though.
The elusive characters who drill holes in them to make table lamps would be in a position to do a movement 'swapsy' but this could entail consorting with people you normally..probably...wouldn't.

Dave
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Old 9th Apr 2020, 8:54 am   #5
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Default Re: AVO 9sx Panclimatic High sensitivity

Quote:
Originally Posted by Techman View Post
Unfortunately I've got bad news.

Virtually every other one of this model of AVO has an open circuit movement. The stock of replacement movements was used up many years ago and you're right at the back of a long line of people looking for this very movement. Even if you were lucky enough to find one, it would just go the same way in the end - it's a 'stock fault' with them and they're well known for it.
That's interesting. I've got quite a few 9SX's in working order.
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Old 9th Apr 2020, 3:42 pm   #6
Nixie tube
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Default Re: AVO 9sx Panclimatic High sensitivity

Thanks to all for your replies. The advice given confirms what I already suspected.
I think though that it is always useful to see if anyone else has another take.
Realistically I agree it seems my only choice is to find another Model 9, as although other Models of AVO share a 37.5uA movement, the scale plate would be a 100/25 design and therefore useless.
I believe the reason that each movement was matched to a particular scaleplate, was a function of the two 'Hair Springs' which,being mechanical, every Hair spring would exhibit slightly different torqe which was non linear. Therefore at production a scaleplate would be chosen to accomodate the error.
This means that scaleplate divisions are actually not linear as would appear.
(Please someone correct me if I'm misinformed on this!)
Someone somewhere will have either a complete Model 9 or a relevant movement. Just gotta keep looking.
This is a meter in lovely condition and I certainly won't be scrapping it!!!
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Old 10th May 2020, 11:06 am   #7
Nixie tube
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Default Re: AVO 9sx Panclimatic High sensitivity

Hi all,
Pleased to say that have now found a suitable replacement from another Test set No1 9sx.
Movement sets up spot on at 3333 ohms and 37.5 microamp fsd.

Thanks again to all for your advice.
Nick.
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