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Old 28th Sep 2017, 8:16 pm   #21
chriswood1900
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Default Re: Which Avometer should I purchase?

If you don't mind an American meter the Simpson ones are good robust, easy to fix with few specialist components, look out for the models with the electronic cutout which is much better than the Avo one it is alleged to be able to protect the meter measuring the mains on any range including Ohms, and finally it is really easy to calibrate with no moving magnet shunts, just a few pots. Also lots of data and service info on US websites.
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Old 28th Sep 2017, 8:28 pm   #22
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Default Re: Which Avometer should I purchase?

I think the chap who sells Avos at all the BVWS events and at radio rallies is Vernon Henton. See the BVWS Members' booklet for postal details (no email). He knows his stuff so his Avos should be a good bet.
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Old 28th Sep 2017, 8:55 pm   #23
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Default Re: Which Avometer should I purchase?

Thanks for the detailed replies everybody - much appreciated.

I'll keep an eye out at a few local events for Vernon Henton. I'm not in a particular hurry so will wait for the right person and meter to come along
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Old 28th Sep 2017, 10:41 pm   #24
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Default Re: Which Avometer should I purchase?

I agree with Richard that the EA113 is an absolute gem. The problem comes in finding one.

When I got mine, the first thing was to put it on the calibratore in the standards lab. DC was fine on all ranges (10mV fsd to 1kV fsd in a 1-3-10 sequence) and valve voltmeter sort of input impedance to boot.
AC was just as good and was pretty flat to 200kHz so it's an audio millivoltmeter as well.

If you see one, grab it!

4 AA cells last for years.

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Old 28th Sep 2017, 11:02 pm   #25
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Default Re: Which Avometer should I purchase?

There's actually one on ebay at the moment thats in pretty good condition. Slightly suspicious markings on the meter face though. I'm not ready to grab one yet without some further research so if anyone wants one, go go go
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Old 29th Sep 2017, 8:03 am   #26
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Default Re: Which Avometer should I purchase?

Mine's been my main multimeter in the radio shack for 30 years and I've found only one problem with it... it's fairly sensitive to any RF in the shack, so a model 8 comes out for fixing transmitters.

For some odd reason, these meters became rather sought after a few years ago and prices went to dizzying heights. I think I paid £15 for mine, so seeing figures over £600 being bandied about for a while mystified me. I still don't know what the attraction was. Our answer to the South Sea bubble?

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Old 29th Sep 2017, 8:34 am   #27
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Default Re: Which Avometer should I purchase?

There are crazy prices out there for no apparent reason. I think people get carried away once, someone looks at the sold price history and decides that's the value, people think it's now scarce because it's expensive and this drives prices up. This is one of the annoyances of the Internet. It used to be possible to get some real bargains. I bought my first scope for £1 (or was it £2) from a car boot sale as an example. Now they're selling broken Japanese radios from the 1980s as "classic" for £30 at them!

I saw a Heathkit GDO go for £166 the other day as a fine example!
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Old 29th Sep 2017, 9:17 am   #28
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Default Re: Which Avometer should I purchase?

All the above is good advice.

If you are willing and able to do some work on it, an Avometer Model 8 might be a good choice. Of the traditional type, the consensus seems to be that the Mk III is the best but the later versions of the Mark II would not be a bad choice either (The early MkIIs do not have a 250V (DC) range). As has already been pointed out, any of these will be at least the best part of 50 years old and therefore quite entitled to expect a bit of care and attention. The Model 8 Mark IV is probably best avoided as the switches use printed discs which can give trouble.

I would not rule out the later types, Marks V, 6 & 7. Despite their perceived reputation for vulnerability to damage, they were subject to a very rigorous NATO testing regime and were in use by the armed services for many years. Some of the issues may have been due to the durability of plastic components from a time when the characteristics of new materials were not yet known. The Mark V does often have problems with the flexible printed wiring but this can be replaced by conventional wiring. A good Mark V is even more accurate than the earlier types. The elastomer boots on the push button switches often perish but were the same as for the Marks 6 & 7 and may still be available.

The Marks 6 and 7 use rigid printed circuit boards and are generally reliable and very accurate. They are however rarer and hold their price well. Until quite recently many parts were still available from Avo at Dover.

The EA113 is an excellent meter but complex if it needs repair. Unfortunately it suffers from Audio Mythological Blight, hence the market price. The calibration of AVO Valve Characteristic Meters mentions the use of the EA113 and this is taken to mean that the magic will be lost if any other meter is used, even if it is equally capable of making the necessary measurements. In a slightly more rational way, the mention of the Model 8 in professional technical manuals is probably the main reason that the later marks stayed in production so long despite a very high price laterally.

All used analogue meters could have been subject to a form of abuse in recent times if they have been used by people who do not appreciate that the are much more delicate than a solid state digital meter which will tolerate being dumped in a tool box along which heavy tools, and in many cases are not expected to last more than a few years. (Nothing electronic does does it)?

New analogue meters are still available at reasonable prices. The Simpson 260 has already been mentioned but the robustness and build quality could be criticised. Metrix/Chauvin Arnould and Gossen Metrawatt (ABB) also both sell good professional analogue meters for under £200 (see for example RS website).

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Old 29th Sep 2017, 9:39 am   #29
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Default Re: Which Avometer should I purchase?

"The calibration of AVO Valve Characteristic Meters mentions the use of the EA113 and this is taken to mean that the magic will be lost if any other meter is used,"

Ah, thanks, that explains it. I'd have thought that testing valves on a VCM calibrated against something using transistors would have tainted them. Perhaps AVO were just wanting to push their latest model? If it's a matter of a high impedance electronic voltmeter, then maybe a CT38 used in the calibration would maintain the purity of the valvishness of the user experience.

Anyway, if the object of the thread is choosing a British multimeter of decent quality, you don't have to stick to AVO, don't forget the GEC "Selectest" models. They were good. They were made by SEI, Salford Electrical Instruments a GEC subsidiary based at the time, despite the name, in Times Mill, Heywood Lancs (It's flattened and now a supermarket site)

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Old 29th Sep 2017, 12:22 pm   #30
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Default Re: Which Avometer should I purchase?

+1 for Selectest they offer an excellent AVO 8 alternative, better in some respects.

When I was at college in the 80s a load of EA113s, probably at least a dozen, were kept locked in a glass fronted cupboard. I don't think the students were ever trusted with them. Didn't realise they'd now become a cult!

There is a companion Heathkit Multimeter to the VTVMs, the MM-1U. However unusually for me I don't think I'd recommend it over a Selectest (and I have both).
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Old 29th Sep 2017, 1:11 pm   #31
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Default Re: Which Avometer should I purchase?

I had a look around for the MM-1U actually. Virtually unobtainable. Would go nicely with my V-7AU
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Old 29th Sep 2017, 1:24 pm   #32
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Default Re: Which Avometer should I purchase?

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Originally Posted by wd40addict View Post
+1 for Selectest they offer an excellent AVO 8 alternative, better in some respects.
Marconi always specified an AVO8 or GEC Selectest in their HF sender manuals, as well as a Keithley DMM for setting up the servo potentiometer voltages (this was the 1980s).

I suppose they were obliged to plug the Selectest!

I have an AVO 9 II as my 'grab-it' always-on-the-bench analogue meter. I got TER to fit a correct rectifier for the a.c. ranges shortly after I'd acquired it, and they checked the calibration.

I was told that the calibration was checked on any instrument as a matter of course, but if I wanted certificated results it would cost me!
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Old 29th Sep 2017, 2:18 pm   #33
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Default Re: Which Avometer should I purchase?

Looking at images, the GEC Selectest looks quite ordered (ie increased accessibility) inside compared to a typical AVO of the era. Access to the movement and scale looks like it might be a long job though.

From what i gather they are deemed 'adequate'. My father worked at Marconi (Baddow) and was never issued with anything other than an AVO, but while i can confirm this i cannot confirm the reason/s.
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Old 29th Sep 2017, 4:45 pm   #34
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Quote:
Originally Posted by Radio Wrangler View Post
Anyway, if the object of the thread is choosing a British multimeter of decent quality, you don't have to stick to AVO, don't forget the GEC "Selectest" models. They were good. They were made by SEI, Salford Electrical Instruments a GEC subsidiary based at the time, despite the name, in Times Mill, Heywood Lancs (It's flattened and now a supermarket site)
SEI. Remember them well. I visited Times Mill more than once with a prototype Range Rover in the back of a truck, before they moved down to Portsmouth. Also a few years ago visited the Morrisons that now stands there.
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Old 29th Sep 2017, 6:01 pm   #35
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Default Re: Which Avometer should I purchase?

I have a couple of SEI spot photometers, they still find use in confirming LDC brightness (60 years after manufacture). Built like a small tank, useful in a fight if needs must (not that i have tried it, or ever want to).
 
Old 30th Sep 2017, 7:59 pm   #36
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Default Re: Which Avometer should I purchase?

If you’d consider foreign meters, the UNIGOR is pretty good. It is a taut-band movement with impressive specifications. I have a couple.
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Old 6th Oct 2017, 2:35 pm   #37
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Default Re: Which Avometer should I purchase?

I have to say I admire your style and if you want to have a vintage test bench all the better. Personally I wouldn’t have a AVO meter given to me, the thought of going back to all that tedious range switching would be painful. Yes your right they are easy to repair, well they would have to be they don’t work very well at the best of times.

I do own an AVO 8 but it probably gets used less than once a year. I think many of the perceived advantage over a DVM are overstated I have no problem tuning for maximum smoke using a DVM. The only time I have found it useful is for comparing the readings on the “trader sheet” to the actual radio on test. The DVM will obviously read high. So I have a AVO 5 and an AVO 8 but I don’t like them. I use them mainly to wedge the door open in summer and very good they are at it.

I awaited the torrent from all that worship at the font of AVO

My Best Regards Chris (Profession Sceptic and Trouble Causer)
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Old 6th Oct 2017, 2:53 pm   #38
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Default Re: Which Avometer should I purchase?

I'm inclined to agree with you after doing much reading and research. After the research and comments on this thread, I turned my attention to a Simpson 260 for this particular use case due to battery availability and general design. Alas you can't get a good one of them either. I've had a MT2017 before and killed it plus I really didn't like it if I'm honest because it wouldn't consistently zero.

This resulted in a whole lot of research, the construction of a really big spreadsheet of meters, head scratching and consulting with the financial director (SWMBO). I ended up with a not insignificantly priced purchase of a new "major brand" bench DMM with a decent AC bandwidth which was far from where the objective started! And I really like it. Going to clear out my DMM collection now and just keep two
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Old 6th Oct 2017, 2:58 pm   #39
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Quote:
Going to clear out my DMM collection now and just keep two
Don't do that, distribute them round the house and vehicles, you never know!

Edit, what bench DMM did you get?
 
Old 6th Oct 2017, 3:08 pm   #40
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Default Re: Which Avometer should I purchase?

I've already got one that lives in the car

Went for a Keysight U3401A in the end. Stings a bit in the wallet department but was thoroughly worth it.
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