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Digital Tube tester compare.

  Model Manufacturer
1
SOFIA 20 Audiomatica, Italy
2
ROEHTEST, Kit version only

Helmut Weigel, Germany

3
ALLADIN II CONAR
4
AT1000 Amplitrex, USA
5
L3-3 with Agilent PC interface. DIY Project.

 

 

 
2) Roe-Test
Homepage
3) Alladin-II
Homepage
4) Amplitrex AT1000
Manufacturer Homepage
5) L3-3

Obsolete Product.

This is a KIT. You must build it yourself. Functionality exceptional high

Under construction.
Almost finished.

This is based on the Testers we bought in 2009 and 2010

With my own build digital interface on it. Under construction. Not for sale here

COLOR SCHEME

GREEN. The winner
Red: The looser
Price
5500 Deutschmark in 1995
Below 100€ for build guide
  For a price of 2400 US$ in 2012, it is the only girl in town.
Cost me 2500 Euro
Repair Support

They offer repairs still after 25 years. Provided they can buy replacement parts needed.

Tester Manual

I WANT TO POST MORE INFORMATION HERE ABOUT THIS VERY INTERESTING PRODUCT. IF SOMEONE WANTS TO HELP ME HERE, PLEASE LET ME KNOW. REAL OWNER INFO IS NEEDED FOR ALL THE WHITE BOXES.
 
Repairs are done, and seem hardly needed.
 
Schematics

Dear Mr. van de Walle,

As Mr. Bigi told you over the phone we do not supply schematics of our products. This a Company policy since 1985 and up to now we had only elements to enforce it.

Best regards,
Maurizio Jacchia. President Audiomatica Srl
(Received By email, 19.07.2011 16:06)

Yes
 
not officially
 
Windows compatible
No
Yes
 
Yes
 
Resolution
16bit. Which is achieved by external D/A converters. So no analog Single Chip inputs. When you go to very low voltage, the Sofia has 100mV offset, which is can be a lot when you test tubes with low grid voltage. I am pretty sure this is a calibration issue. So the tester itself can not be blamed after 20 years.
   

10bit, and I can confirm it is really there and no offset problems. However it is not enough.

Also, it is presented better than it is. For instance 6SN7 tests in steps like this: 2550, 2650, 2750. The last two digits are for the birds, they are always xx50.

 
Measurement range Anode Absolutely AMAZING. It can do 0...700V DC, 250mA
Anode: 0-51 V, 0-306 V. Optional: 300-606 V. Each range 250 mA
 

75...495V

Below 75V not possible

0..250V at 100mA

300V at lower current

Measurement range G1  

0-5.1V, 0-51V. Each 5 mA.

This is not enough for large triodes. Some tubes need -140V. 300B needs -60V.

     
Measurement range G2   0-306 V, 51 mA     0..250V
Measurement range Heater

Filament 0..24V 5A (Wow!) and Current measurement included.

Filament: 0-12,75V, 5A. 0-127 V 500mA.

 

12,6 Volts is not enough.

 
PC and or stand alone
Only PC
Only PC
 

Both. PC only windows.

ALSO there is a large display in the machine, indicating many data.

 
HARDWARE
   
 
Shorts test
No. This is dangerous. one day you plug in a shorted tubes, or you connect something wrong, with those loose cables.
Yes.
 
Yes.
Any short tets, it can be done. Even has an electronic nano ampere mater for this.
Gas test
No, See above, because a gassy tube may short spontaneously.
   
Yes
 
Hazard Lamp
Yes
   
No
 
Sound Test
No
   
Yes
 
Hardware access to all tube connections
Yes, by hand switching
Yes, with full relay matrix
 
Only Plate, Cathode and 1st grid. Several tubes can not be tester.
 
Dust proof cover
No
Depends on yourself.
 
Yes
 
Measure Filament current
Yes
   
No
 
Hardware Quality

Hardware is very good. No fan. What I like, there is almost no micro stuff in there. Even IC's. So if you damage something, you have a good chance to fix it yourself.

The "secret" schematic issue, I accept during normal production, but not if production is stopped. For me personally, I would never buy an new production This Of course this is my personal opinion only. If you buy a new product that they refuse to give you the schematic, you are free to feel good about this.

Depends on yourself.
 
Very good, but the Fan is definitely too loud.
 
SOFTWARE
   
 
Software updates
No. Version 2.1 for DOS is available from the Audiomatica Website, but this is not an update, it is very old.

You download the sofware for free.

Not compatible with very old models.

  Updates. What updates?  
Curve tracing
Curve charts are drawn the way they are supposed to look, right away. Scaling can be done afterwards, even if STORED curves. Wow!!!! This is an EXCELLENT Software job.
Optics of the curves not as nice as the SOFIA. It has the "Excel Look" like Amplitrex has, but options and possibilities are the best of the best. What is missing is the classical curves as you see in any datasheet. Yet is measures very interesting, and professional.  
By default it draws only one curve. Yes, but it needs a lot of trial and error before you have the curves drawn the way the should look. I am not so enthusiastic about this. Also the "Excel look" of the curves is not nice.
 
Speed Once the test is started, the curves are plotted after just seconds. Dynamical and static data is derived afterwards from the curves. Excellent feature: When you press"start" too quickly, curve plotting is auto delayed until the tube heater appears warmed up. This is done by monitoring the heater current draw. (Checked it with a scope) Great software job.     The AT1000 is not very fast. Depending on what you do, the Sofia can be 10x faster, and produces higher resolution in any case.  
Review saved results
Another top class feature of this software. You can save the charts to disk, and you can change the scales afterwards. So you zoom in and out. Like test the tube from 0....600V. Another day, you can plot a curve from 0...200V only, it uses the original measurement. EXCELLENT Software job.
 
Yes
 
Tube parameters at multiple operating point

Wow! A most remarkable feature is used here. You can move a marker around in the curves, and you get all tube data at the specific operating point. Even in STORED curves you can do this later. So you use a 300B at 320V or at 480V, and that makes a LOT of difference. Amazing this part of the software works still under XP. Check here how to install that freeware.

No.
 
No.
Yes
Save curves in graphics format
Yes. The are stored in bmp format, so you don't loose the resolution.
 
No.
 

Software Maintenance

One major bug, see below. For the rest, I found nothing to improve.
Very good. This is living software, suggestions and improvements are implemented in the next versions. Perfect attitude.  

Many things are not elegantly done, or not done at all. I reported many issues and small items, My impression is, Amplitrex is not interested in improvements. Don't think I never tried, but it was a waist of my time.

 

Software (1)

Pentode curves

Whatever you like. Even specify Ultra Linear percentage
Yes
 
No. This an error. Testing them triode mode, is not the real thing. Problem Reported to Amplitrex, it seems technically possible, I have a working test version, but that is all. It was not implemented in an update.
 

Software (2)

Diode Curves.

Yes
Yes
 

Officially the answer is No. I found a way to do it myself, even for twin diodes.

 

Software (3)

Grid voltage

for DHT tubes

Grid voltage is measured wrong for Directly Heated Tubes. The effective grid voltage the tube sees, in increased by half of the filament voltage. This was not compensated in the software. (Though this would have been very easy to do).

So when the tester draws a -1Volt line for a 300B, it is in reality the -3,5 Volt line. Same error is made with the normal"Tube Test" page it produces. With the Sofia, thinking of an improvement is 20 years too late of course.

 

 

Grid voltage is measured wrong for Directly Heated Tubes. The effective grid voltage the tube sees, in increased by half of the filament voltage. This was not compensated in the software. (Though this would have been very easy to do).

So when the tester draws a -1Volt line for a 300B, it is in reality the -3,5 Volt line. Same error is made with the normal"Tube Test" page it produces. With the Amplitrex, I only report it here, for everbodies interest, but reporting it to Amplitrex has only resulted in a work-around advise.

 

Software (4)

Transconductance

     
This is an issue with the AT1000 only. In the stand alone mode, Fixed Bias, the transconductance is represented in percent (of something). Problem is transconductance (in percent!) is only meaningful at 100% plate current. However at Fixed bias, 100% plate current is a matter of coincidence.
 

Software (5)

Emission Test

You can simulate it with set ups.
You can simulate it with set ups.  
Though the software is telling you "Emission" and even shows this in percent, it is actually not measuring Emission at all. Just measures plate current and calls this Emission. That's a real slip.
You can simulate it with set ups.
Matching
Yes. Most excellent method used, which is a MASTER EXAMPLE of engineering quality. This method if HIGHLY RECOMMENDED to study, for every one who wants to make software for tube matching. So you can test 100 tubes, and the software tells you what tubes have CURVES that fit well to other tubes. Not just one or two test points, but full CURVES matching.
Helmut Weigel writes me, this is in the medium term planning  
No. You have to decide for yourself if what you see is a good match or not.
 
Quality Control
Yes. So the tester tells you if a tube is good or bad.
   
No. With "quality control" I expect the tester to tell me if a tube is good or bad. The Amplitrex does not say so.
 
Export of Test report
Yes. by hand or auto mode. Saves a bitmap
   
No
 
The future of this software
The Microsoft Gods have decided not to allow direct access to the RS232 ports in all Windows Versions, meaning the Sofia can only run under DOS. However as MS obsoleted DOS, with the coming of W7, something nice took place: The open source community started to make DOS emulators. These all have the problem that Windows per definition will not allow direct access to the RS232 and LPT1 port, and besides, DOS expects an RS232 mouse on COM1, and nothing else. I see good progress with newer DOS emulators. Right now a 100% good solution does not exist. Use an old DOS PC for your Sofia is the best.
   

The software uses Microsoft internal modules, like MSCHART, etc, which is part of the microsoft Operating system. However these are very old microsoft modules, and I I don't know what happens if one day, the Microsoft Gods decide, newer versions of Windows do not need compatibility with the old versions.