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ECH83

Information - Help 
ID = 2048
       
Country:
Europe
Brand: Common type Europe tube/semicond.
Tube type:  Triode-Heptode   Frequency converter   Controlling (mu) 
Identical to ECH83 = 6DS8
Similar Tubes
Normally replaceable-slightly different:
  CV2128
Different maximum ratings:
  ECH81
First year 1957 Tube leaflet collection E.Erb Analysis by original leaflets
First Source (s)
Aug.1957 : Funkschau # 15

Filament Vf 6.3 Volts / If 0.3 Ampere / Indirect / Parallel / series AC/DC /
Description

According to our profound investigations and tests, the tubes ECH81 and ECH83 are equal - not even tested differently, but only stamped differently. They naturally show different values for a different usage (volts anode). See this forum article here about that.

 
Text in other languages (may differ)
Tube prices 8 Tube prices (visible for members only)
  ech83.png
  ECH83: Courtesy Bureau Belper (De Muiderkring, Bussum), Scan Frank Philipse
Karel De Reus †
 
ech83_r.jpg
ECH83: Collection JR
Jacob Roschy

 
no17_1.png
ECH83: RTT 1974 (Franzis) 13. Auflage
Martin Renz

 
ech83_kenn_im.png
ECH83: Röhrenkartei der Funk-Technik
Iven Müller


Usage in Models 1= 1957?? ; 4= 1957 ; 2= 1958? ; 7= 1958 ; 10= 1959? ; 23= 1959 ; 9= 1960?? ; 9= 1960? ; 27= 1960 ; 4= 1961?? ; 17= 1961? ; 27= 1961 ; 7= 1962?? ; 47= 1962? ; 21= 1962 ; 5= 1963?? ; 11= 1963? ; 7= 1963 ; 1= 1964?? ; 1= 1964? ; 1= 1964 ; 6= 1965?? ; 12= 1965? ; 1= 1968? ; 1= 1969? ; 1= 1969

Quantity of Models at Radiomuseum.org with this tube (valve, valves, valvola, valvole, válvula, lampe):262



Forum contributions about this tube
ECH83
Threads: 2 | Posts: 17
Hits: 3353     Replies: 0
ECH83 = ECH81 - oder ?
Jacob Roschy
12.Sep.10
  1

Im Thread „ECH83 versus ECH81 wird eindeutig nachgewiesen, dass die Röhrentypen ECH81 und ECH83 völlig baugleich sind und unter gleichen Bedingungen auch innerhalb normal üblicher Streuung die gleiche Charakteristik haben.

Demnach wurde also die physikalisch gleiche Röhrentype, die als ECH81 zum Betrieb an Spannungen im Bereich 100...250 V in normalen Netz- Rundfunkempfängern verkauft wurde, als ECH83 zum Betrieb an Spannungen im Bereich 6...14 V für Autoradios angeboten.
 

Kann man nun behaupten ECH83 = ECH81, also völlig gleich ?
 

Nach physikalischen Gesichtspunkten ja, aber nach kaufmännischen und juristischen Gesichtspunkten muss man eigentlich sagen: nein !
 

Denn, trotz völliger Baugleichheit gewährleisten die Hersteller nur bei der ECH83, dass diese bei den niederen Spannungen von 6...14 V die propagierten Leistungen erbringt, aber sie müsste nicht mehr bei Spannungen von > 100 V funktionieren, wie für die ECH81 gefordert.

Es ist auch kaum vorstellbar, das die als ECH83 angebotenen Röhren nicht sorgfältig auf ihre Eignung für diese niederen Spannungen geprüft wurden.
 

Umgekehrt wird für die ECH81 gewährleistet, dass sie bei Spannungen im Bereich 100 ... 250 V ihre optimale Performance bringt, aber sie muss nicht mit Spannungen unterhalb von 20 V zufriedenstellend funktionieren.
 

Demnach ist die Angabe ECH83 = ECH81 nur eine oberflächliche Aussage, die nicht alle Aspekte berücksichtigt.

Richtig wäre für die Verwandtschaft zwischen ECH81 und ECH83 die Angabe: «baugleich, aber andere Spezifikation»


 

M. f. G. J. R.


 

 
Hits: 38396     Replies: 15
ECH83 versus ECH81
Lars-G. Lundelin
10.Dec.07
  1 Hello Radiofriends! When hunting around for suitable tubes, I stumbled over a very interesting case. A seller claims that the ECH83 tube is almost identical to the ECH81 despite the voltage difference in the anode circuit.In other words you can substitute the ECH81 with an ECH83. A sceptic buyer couldn't believe this and the seller refer to the this URL:http://www.g4jcp.freeserve.co.uk/pw/jun01.htm Well, What do the experts say about this? With kind regards Lars-G.

Editing 13.12.07 EE = change of title only.
Dietmar Rudolph
10.Dec.07
  2 The ECH 83 is a low voltage tube. It works with only 12.6 V anode supply, especially for car radios.  This was an intermediate solution at times when transistors were not able to work on higher frequencies.
The pins are identical to ECH81 but that is all.

Kind regards, Dietmar
Ernst Erb
10.Dec.07
  3 I think we have to go into this deeper. Therefore I have written to Dietmar to dig into it before coming to the conclusion that only the pins are identical. I'm sure he will come back with a good answer with proofs - anyway.

Addition 11 Dec 07:
I have also asked Wolfgang Holtmann and Roy Johnson if they want to dig into this question methodically. We know already one thing:

Roy has an ECH81 plus an ECH83 with the type code YD12 - and the same for YDD (Batch code Z8E2 and ZGG3). Both YDD are made by Tungsram but the Z8E2 is labelled Mullard.

So all the 3 might come up with facts here - but no more "cooks" please - or then via eMail to them or to me. Thank you.
Meyer Rochwerger
10.Dec.07
  4 Dear friends,
The
attached picture illustrates Dietmar's point.

Meyer

Attachments

Ernst Erb
10.Dec.07
  5 Dear Meyer
These differences "everybody" knows - it has only to do with what you feed to the tube (normally).
Please wait with any answer until Dietmar plus Roy and Wolfgang have finished their research I asked for - but then it is not any more necessary ;-). We don't want "jumping to conclusions". This should not be offending because it is obvious that one can come very easily to wrong conclusions in such a situation.

Additions (in maroon):
13.11.07:
1)
There were about 10 posts from different persons (not from the 3 cooks here) - despite of my "warning" that this has not to be done in this thread. I deleted all of them. The way how to help here is given in my posts.

2)
Since I think (but only as a mere possibility) it can be that at "first time" selected ECH81 could have been used and that later production changes were made where the rule to not feed more than 30 volts is valid - we ask for a listing of Brand, Type code, Batch Code and -Date (where you know) to be poste on a new "Talk" thread. I will ask the same in German.

3)
In Post 3 I will publish a short summary about our findings after all 3 authors have agreed that we have a real solution - or whatever the final answer is.

4)
We might have similar questions on otehr tubes but this is a case for new threads posted from that tube.
Dietmar Rudolph
11.Dec.07
  6 Next week I will be able to make comprartive measurements of ECH81 / ECH83 with a curve tracer, similar to the case of the ECF11.

Fortunately, I found 2 specimen of ECH83 in my tube collection, besides several ECH81. So the test can be done.

From the similarity of the curves it will be seen whether or not the thesis that ECH83 be a selected ECH81 is plausibel.

Remainig questions are:
  • What are the criteria for such a selection?
  • Why creating a new type ECH83 instead of adding an additional working point for ECH81?
  • Do the tube testers have different or the same set of instructions for both types?
The last question being a pragmatical approach.

Best regards, Dietmar
Roy Johnson
11.Dec.07
  7

This has raised some interesting points and a first quick test indicated very similar current and conductance values at low voltages also on the ECH81 which gives credence to the intial article. 

Examination and Coding 

Physical examination of some tubes from the Mullard/Philips/Tungsram group where most tubes are marked with type and batch codes was undertaken.  The results for 12 ECH81 and 19 ECH83 tubes are shown in the following table.

The type code is the first set of letters/numerals which indicates the tube type before it is printed with the usual large logo and type information; this is followed by a second set of letters and numbers which are a manufacturing site, date and batch code.

Tube Ref
TYPE
Type Code
Batch Code
Brand
Manufactured
 
 
 
 
 
 
A1
ECH81
?D1
?41?
MULLARD
NON-UK
A2
ECH81
YD1
B5J
MULLARD
UK Blackburn
A3
ECH81
YD1
B5H
MULLARD
UK Blackburn
A4
ECH81
YDD
Z8E2
MULLARD
 TUNGSRAM
A5
ECH81
YD1
B5J
MULLARD
UK Blackburn
A6
ECH81
YD1
B6D
MULLARD
UK Blackburn
A7
ECH81
YD1
B3?
MULLARD
UK Blackburn
A8
ECH81
YD1
B6F
MULLARD
UK Blackburn
A9
ECH81
YD1
B5C
MULLARD
UK Blackburn
A10
ECH81
YD1
B4B1
MULLARD
UK Blackburn
A11
ECH81
DN
YDZ
MULLARD
NON-UK
A12
ECH81
DN
YDZ
MULLARD
NON-UK
 
 
 
 
 
 
B1
ECH83
????
B2A2
MULLARD
UK Blackburn
B2
ECH83
YD12
B??
MULLARD
UK Blackburn
B3
ECH83
YDD
Z9G3
TUNGSRAM
B4
ECH83
YDD
*2G1
MULLARD
Philips Holland
B5
ECH83
NJ1
B1J1
MULLARD
UK Blackburn
B6
ECH83
NJ1
B1J2
MULLARD
UK Blackburn
B7
ECH83
NJ1
B0J
MULLARD
UK Blackburn
B8
ECH83
???
B2A4
MULLARD
UK Blackburn
B9
ECH83
YDD
Z8G3
TUNGSRAM
B10
ECH83
NJ1
B1A
MULLARD
UK Blackburn
B11
ECH83
NJ1
B1C
MULLARD
UK Blackburn
B12
ECH83
NJ1
B9F
MULLARD
UK Blackburn
B13
ECH83
NJ1
B0J
MULLARD
UK Blackburn
B14
ECH83
NJ1
B9E
MULLARD
UK Blackburn
B15
ECH83
NJ1
B9L
MULLARD
UK Blackburn
B16
ECH83
NJ1
B8I
MULLARD
UK Blackburn
B17
ECH83
NJ1
B9D
MULLARD
UK Blackburn
B18
ECH83
NJ1
B9E
MULLARD
UK Blackburn
B19
ECH83
NJ1
B9D
MULLARD
UK Blackburn

The only type coding in common to both the ECH81 and the ECH83 is the YDD code for tubes made by Tungsram.   

Measurements

Tubes were selected from new stock and it is believed that they are all unused and initial tests against the manufacturers ratings indicated that all were better than average new figures.   They were tested on an AVO characteristic meter at 3 voltages of screen and anode and at a grid voltage of -0.2.     The following results were obtained for 4 of each type.

ECH83 Results

VOLTS
 
ECH83   B2
ECH83   B3
ECH83   B8
ECH83   B9
AVERAGE
 
 
Triode
Hexode
Triode
Hexode
Triode
Hexode
Triode
Hexode
Triode
Hexode
12V
Ia
1.2
1.0
1.5
1.15
1.5
1.4
1.8
0.9
1.5
1.1
 
gm
0.8
0.5
0.9
0.6
1.1
0.7
0.7
0.5
0.9
0.6
 
 
 
 
 
 
 
 
 
 
 
 
20V
Ia
2.2
1.9
2.5
2.0
2.6
2.2
2.9
1.9
2.55
2.0
 
gm
1.0
0.6
1.0
1.0
1.4
0.9
1.0
0.8
1.1
0.8
 
 
 
 
 
 
 
 
 
 
 
 
30V
Ia
3.6
3.2
4.0
3.4
4.0
3.5
4.4
3.2
4.0
3.3
 
gm
1.4
0.9
1.4
1.3
1.6
1.0
1.2
1.1
1.4
1.1

  
ECH81  Results

VOLTS
 
ECH81   A4
ECH81   A5
ECH81   A7
ECH81   A9
AVERAGE
 
 
Triode
Hexode
Triode
Hexode
Triode
Hexode
Triode
Hexode
Triode
Hexode
12V
Ia
1.1
0.8
1.0
1.0
1.4
1.3
1.3
1.3
1.2
1.1
 
gm
1.1
0.6
1.0
1.0
1.1
0.7
1.1
0.8
1.1
0.8
 
 
 
 
 
 
 
 
 
 
 
 
20V
Ia
1.9
1.5
1.8
1.8
2.4
2.2
2.3
2.1
2.1
1.9
 
gm
1.4
1.0
1.2
1.2
1.4
0.9
1.3
1.1
1.3
1.1
 
 
 
 
 
 
 
 
 
 
 
 
30V
Ia
3.1
2.9
3.0
3.0
3.6
3.5
3.3
3.5
3.3
3.2
 
gm
1.7
1.5
1.6
1.6
1.9
1.2
1.8
1.5
1.8
1.5

COMPARISON OF AVERAGE RESULTS

VOLTS
 
ECH83   AVERAGE
ECH81 AVERAGE
 
 
Triode
Hexode
Triode
Hexode
12V
Ia
1.5
1.1
1.2
1.1
 
gm
0.9
0.6
1.1
0.8
 
 
 
 
 
 
20V
Ia
2.55
2.0
2.1
1.9
 
gm
1.1
0.8
1.3
1.1
 
 
 
 
 
 
30V
Ia
4.0
3.3
3.3
3.2
 
gm
1.4
1.1
1.8
1.5

The average anode current figures for the triode are some 17 to 20% lower for the ECH81, but less than 5% for the hexode.  The average mutual conductance (gm in mA/V)   are higher for the ECH81.

These figures are based on limited measurements for only four of each type and the spread within each type is as great as the difference between the average values.   

 Conclusions

Identical codings have been seen on ECH81 and ECH83 tubes.

There is an apparent though small consistent difference in the characteristics.

Failure of the ECH83 at high voltages could indicate a constructional difference.

Since these are the results from a limited examination, the differences are not statistically significant.   It would be useful to assess further examinations and tests; in particular, codes on the Philips group tubes and possibly physical examination of the construction.   If members have these types perhaps they could report the codes by mail so that we can get a better overall view.

The full characteristic graphs will also be interesting if these can be extended in voltage for the ECH83 to determine any breakdown mechanism.     

It would also be interesting to try an ECH81 in a low voltage car radio.  The conversion conductance may be different between the two types,  but not easy to measure without a special r.f. test set-up.

Best regards to all,

Roy

 

Wolfgang Holtmann
11.Dec.07
  8

As Mr. Konrad Birkner already suggested,

I made a direct comparison between the ECH81 and ECH83, both with the “YD” code. To keep it simple, only the triode section was tested.

The plots of the static transfer characteristic was used as reference.

 

To be sure my own ECH83 (Philips) is in good condition, the red trace is quite nicely in shape with the Philips publication. Test voltage was 25 V. See below.

 

 

 

The next step was to compare the behaviour of the very same ECH83 at Va = 100 V, as given for the ECH81.

Again, almost no difference in the transfer characteristic of my ECH83 in comparison with the ECH81 data is visible.

 

 

 

We have to make a sacrifice!

To be on the safe side, I opened both tubes to look for any differences in the system itself. Even with a magnifier glass nothing worth to mention !

 

 

My conclusion:

There is no difference in construction(!) between those two tubes!      

 

Attachments

Wolfgang Holtmann
13.Dec.07
  9

Having regard to Mr. Roy Johnson’s Tests at Higher Voltages,

I would like to add my similar tests of the remaining two ECH83 (Philips Miniwatt, Made in Holland) with coding:

 

YD12         = ECH81, Rev.12

A4D           = WIRAG, Wien, April 1964

 

YD0           = ECH81, Rev.0  (could be read as “C”)
(tri) 1H3     = triangle for PHILIPS Heerlen, Aug. 1961
       

 

When we look into the data sheets of the ECH83 and ECH81, one gets the impression we are dealing with two different tubes. It is quite understandable, better performances at low supply voltages can be obtained by reducing the spacing of the electrodes in the first place! On the other hand, this has influence on the maximum allowable Va and Vg2+4 for the heptode section and Va triode as well. In fact, for the ECH83 compared with the ECH81, they are up to ten times lower!

 

 

More details

Because of the same geometry inside, I was quite sure my ECH83’s (“YD”) will survive voltages ten times higher as allowed.

 

Important Note:

Normally, it is always highly recommended to pay full attention to the published maximum ratings!

 

However, in this case of doubts, I dare to take it a step further.

Bearing in mind the maximum values given for the ECH81, a bench test set-up was easily created. The negative bias was set for an anode current of 0.9 mA for the heptode and 0.1 mA for the triode.

 

 

In order to detect almost invisible internal sparks as well, I connected capacitors at the anodes and g2+4. They are fed to an Audio-Amplifier with speaker. With the added current limiting resistors, any malfunction should be discovered by this.

----- What a beautiful silence ....

 

  My two ECH83’s passed the Vmax = 300 V test as stated for the ECH81.

 

 

Remarks:

All my findings are focussed on the ECH83 with the “YD” code!

I have at the moment no “NJ” types in my possession. Perhaps they may react in a different way !?

Dietmar Rudolph
19.Dec.07
  10 First results of measurements with a TEK curve tracer can be presented now.

The data for these measurements are:
  • Triode (left hand side): U = 20 V / division, I = 2 mA / division, Rload = 6.5 kΩ
  • Heptode (middle): U = 50 V / division, I = 0.5 mA / division, Rload = 85 kΩ;  Ug2g4 = 100 V
  • Heptode (right hand side): U = 50 V / division, I = 2 mA / division, Rload = 25 kΩ;  Ug2g4 = 100 V
All valves were Valvo types. (For "YD7 +4+", the "+" should read "=" with "|" in its middle.)

Please note: for both ECH83 and ECH81, the maximum voltage at the heptode section was 500 V!

From these traces, it can be concluded:
  1. There is no gas inside the ECH83. Else its curves would break down far before 500 V are reached.
  2. The curves for the ECH83 and the ECH81's are very similar.
  3. These results support the assumption or thesis that the ECH83 be a selected ECH81.
A pre-test was done with reduced voltage and current, and with different valves, as shown here.



At the high voltage measurement, a resistor of 10 kΩ was put at the screen pin. This was for protection only. However, the resistor makes the valve operate with a gliding screen voltage. So this curves are not directly comparatible to the curves in the first figure.
However, further measurements will be done by Roy and Wolfgang in order to get additional information, although the thesis probably cannot be proved with any degree of certainty.

Best regards, Dietmar
Wolfgang Holtmann
20.Dec.07
  11

We saw in the past:

 

n      ECH83 and ECH81 with the same coding “YD”

n      Even the Production Change (Revision) Code “YD D” is sometimes equal

n      No great difference in system geometry between the Philips make ECH83/81

n      The characteristics are (nearly) equal *)

n      It turned out, the ECH83 has in fact no lower Vmax limitations

 

*) Several ECH81’s (NIB) are checked (plot of the Ia-Vg curve, Heptode and Triode section separately tested) against the ECH83’s factory statements.

My results: equal or even better current flow at 12.6 volts !! 

 

 

 

The proof of the pudding….

Up to now we didn’t make a functional test under real receiving conditions! This ultimate test would prove, whether the hf-qualities between the ECH83 and ECH81 are equal too?

Suddenly I remember some experiments done with a breadboard mixer-circuitry a few years ago. The goal was to test the electrical performance of “Ersatz” vintage mixer-tubes difficult to find.

 

In the Philips Data Sheets I discovered a test circuitry around the ECH83:

 

 

With some minor modifications I tested all my ECH83’s and ECH81’s at 12.6 V and 6.3 V using the schematic as shown below:

 

 

The IF-output signal (470 kHz) is fed to a Selective AC-Voltmeter tuned to that frequency. At 6.3 V the output signal is 4.5 dB lower.

 

Conclusions:

No significant difference in the ECH81’s hf-performance in relation with the ECH83’s !

Believe it or believe it not, even with the supply voltage reduced to 3 V both tube types are still functional!    

 

Attachments

Roy Johnson
21.Dec.07
  12
1. MEASUREMENTS
Measurements have been made on an AVO VCM163 characteristic meter on a total of 33 ECH81 and ECH83 tubes. 
 
They have each been tested under the operating conditions recommended for each type of tube with a total of 8 measurements for each. The standing anode current and the mutual conductance for both the triode and the heptode sections were measured.
 
The table below shows the averaged results.   Ia is in mA and gm is in mA/V.
 

 
Type
Tested as ECH81
Tested as ECH83
Triode
Heptode
Triode
Heptode
Ia
gm
Ia
gm
Ia
gm
Ia
gm
ECH81
6.27
2.11
5.44
1.99
1.16
1.01
1.02
0.66
ECH83
6.64
2.02
5.59
1.94
1.19
1.09
1.06
0.72

 
The differences between the ECH81 and the ECH83 are insignificant and much less than the variation between individual tubes or the spread within each type.
 
The full table of results is HERE.
 
A plot of all 264 measurements is shown HERE on a logarithmic scale. 
 
The average values were calculated for each of the parameters and is shown below each of the sections of the table. Some tubes were clearly used and the results were excluded from the averaged values.
 
The conclusion is that measurements at high and low voltage show no significant difference between the two types.
 
 
2.   UK SERVICES SPECIFICATION
The type specification CV2128 is met by the ECH81.   It is significant that the testing procedure for acceptance of the CV2128 calls for 100% testing at low voltage as well as high voltage.
At screen and anode voltages of 15 and the grid at zero voltage, the minimum acceptance currents are 18mA and 35mA respectively for the triode and heptode sections.
 
This indicates that the ECH81 was deemed suitable for low voltage service. It is also significant that there was no ECH83 services specification.  The date of the second edition of the specification is May 1953 which shows that the usefulness of the ECH81 at low voltages was recognised at an early stage.
 
 
3.   The only contrary indication to the two types being identical is a paper by Prof Osmo A Wiio of Finland. In a paper kindly supplied and translated by Åke Nyström.  
Wiio states in talking about the low voltage tubes:-
 
…..it is possible to achieve workable S-values with low anode voltage. When the grid has been placed closer to cathode, the required results are achieved. Only the ECC 86 tube utilizes different special technology ……..
 
A fuller translation is HERE.    
 
4.   I am still reviewing the tube codes and the dating and  shall report shortly on these, but if anyone has ECH81 and ECH83 tubes of Mullard, Philips or Tungsram manufacture, I would still appreciate details of the codes (etched on the glass) by e-mail so that we get a complete picture.  Thank you.
Best regards,
Roy
Wolfgang Holtmann
17.Apr.08
  13

We are happy to welcome another cook in the kitchen: Mr. Gerhard Eisenbarth.

He was involved with the development of electron tubes at the LORENZ factory.

He has the knowledge and equipment to perform further examinations especially with his own Stereoscopic Measurement Microscope!

 

It was Mr. Erbs idea to initiate a „blind test“, in order to get nearer to the real background of the –possible- differences between the ECH81 and ECH83.

An independent measurement of the electrical and physical qualities was the goal. 

He sent me a mixed variety of 11 tubes with all factory markings removed!! Only numbered.

I added an ECH81 and ECH83, both from Siemens with the same coding YD8!

 

My task was to record the transfer characteristics of each system at high tension (HT) and at low tension (LT = 6.3V) as well. Please see below. 

The next step was the physical measurements, to be carried out by Mr. Eisenbarth. He will reveal his findings shortly.

 

Notes:

-- A warm-up time of 1 minute was allowed of each tube measured.

-- Tube No. 3 and 10 showing unusual characteristics (wear & tear)

-- To minimize overlapping of curves, I subdivided each group (1 & 2)

-- A weighting of these curves will be done later.

 

 

Gerhard Eisenbarth
21.Apr.08
  14 Project ECH81 versus ECH83 - Measuring of System Dimensions


We started a project with the question: "What is the difference between the tube ECH81 and ECH83.
Before we present our results, I would like to show how I and what resulted. For a double blind test Wolfgang Holtmann has sent 13 tubes without any marking and with the tips broken.

My task was to measure the systems of each tube to find out differences in dimensions. Wolfgang did not send me his findings nor did he tell me some results.

I opened each tube carefully in a way that I could measure the systems with my stereo measuring microscope.
The selectable zoom factors are: 5x, 10x, 20x, 40x In the highest level of magnification I can dissolve 0.0025 mm per division.
Wire diameters and thicknesses have been tested with a micrometer of a resolution of 0.01 mm per division.

Below are the isolated system parts from a tube.






The following picture shows how a grid is positioned under the stereo-microscope to measure each grid position or the differences of distances between each wire.







The minutes of measuring a tube is shown in the picture below. This has been done for each tube received.




In the table below you find the relevant distances between electrodes of the heptode systems of all 13 tubes.






All system components of the tubes are stored which enables us to do further mechanical measurements if necessary.

Wolfgang Holtmann
25.Apr.08
  15

No.      Type               Brand             Code              Remarks

 

1          ECH83           Tungsram      ENO

2          ECH81           Tungsram

3          ECH81           Siemens

4          ECH83           Siemens        YD7-*30         München

5          ECH83           Mazda            NJ?-Aj811    

6          ECH83           Valvo              NJD-D2B

7          ECH81           EuroValve     

8          ECH83           TFK                B8201900

9          ECH81           Valvo              YDC-D1B

10        ECH81           Philips            YD11-A0B

11        ECH83           Valvo              YD7-*3G

12        ECH81           Siemens        YD8-*7G        München

13        ECH83           Siemens        YD8-*9B        München

 

ECH81

Tubes No. 2,  3,  7,  9,  10,  12

 

ECH83

Tubes No. 1,  4,  5,  6,  8,  11,  13

 

 

John Kusching
06.Jul.15
  16

I received this message from guest Robert J. Sutherland:

I believe I have an original contribution to make to the forum discussion on the ECH81 vs the ECH83. Most if not all contributors appear to have encountered "YD"-coded crossovers of ECH81 to ECH83, but I have just acquired a Mullard ("British made") example with the etch code "NJ R9K?" (where '?' indicates illegible") that is clearly labeled "ECH81". (Incidentally, the 'R' is definitely such, and not a partial 'B', so the manufacturer is Mullard Mitcham.)

Investigating this apparent anomaly, the possibility of which I was not previously aware, took me to the discussion on your website.

One may speculate that the labelling in this particular case may be either due to the valve failing in some way to meet the necessary low-level performance required of an ECH83 (although one might wonder whether the necessary level of testing would be cost-effective for a consumer item) or (more likely) that the manufacturer was simply making up a shortfall in ECH81's by "re-purposing" ECH83's, and was content to do so in the knowledge that any difference in high-voltage performance would lie within normal tolerances. Which does rather beg the question; not merely the one raised in the forum as to why bother to introduce an "ECH83" at all, but beyond that, why take even more trouble to manufacture it as a distinct entity? (As clearly was done.)

Nevertheless, the above "ECH81/NJ" conjunction is, I believe, clear evidence that the manufacturer was comfortable with having an ECH83 operate at high voltage.
 

 
ECH83
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