Exhibits details 6

As to keep pages within reasonable limits we have decided to introduce a new Exhibits details 6 webpage

Succeeding details page 5


Initiated on 22 January 2014

Status: 12 May 2014

2aC extended topic

1 New supplement


We would like to start with a curious meter, which most likely was to be operated in conjunction to high tension systems like was for radar maintenance.

(1) New supplement


This test set arrangement is kept in a handsome tray, which Bakelite body is insulating it adequately against environment

Visiting Günter Hütter on 7 May 2014, this to me unknown meter type was discussed. He instantly responded: Don't you know this type? My replay was, NO!

Then he very kindly copied a book page, which by itself might have been the nth copy of a copy. It tells us: Prüf-Universalmeßinstrument PUm 2

Baumusterbezeichnung     PUm 2

Anforderungszeichen        Ln 26744

Verwendung                        Dient zum Prüfen der Ströme und Spannungen an Geräten

Dv. und Beschreibung

Betriebsarten                        1. Messung von Gleichstrom und Gleichspannung (Drehspulmeßwerk).


                                                 a) Gleichstrom 2 mA, 6 mA, 30 mA, 120 mA, 1,2 A, 6 A 12 A mit Paralellwiderstand 60 A

                                                  b) Gleichspannung 100 mV, 6 V, 30 V, 60 V, 300 V, 600 V

                                                   2. Messung von Wechselspannung bis 10 000 Hz (Drehspulmeßwerk mit Gleichrichter)

                                                    Meßbereiche Wechselspannung 6 V, 12 V, 60 V, 300 V, bei 6 V, 12 V, und 60 V ist Z = 7500 Ohm, bei 300 V ist Ri 107 500 Ohm

                                                    3. Messung von Wechselstrom und Hochfrequenzstrom (Drehspulmeßwerk mit Thermoumformer) The meter shown above on the left-hand side

                                                        Meßbereiche 2 A, 6 A  


Viewing the empty tray or box. The two meters being removed

On the far left-hand side a 60 Amps shunt being stored.


The 60 Amp shunt is to be connected onto next shown meter and its range is to be set at range of 2 mA


What I never before have noticed is that the instructions how to handle- and operate the test set is being kept at the backside of the tray (box). The instruction plate can be taken out sideward


The two test meters being assembled outside its tray

On the left-hand side a HF current meter using a so-called Thermoumformer also known as a thermo-couple. 


This dual instrument is to be on the left for dc- and on the right-hand side for ac; both for current- as well as voltage measurements. The ac facility could be operated up to 10,000 Hz

Both instruments are entirely insulated against one another

Quite curious - nowhere is an indication who might once have developed it.


On  5+8 March 2014

2aC extended


 My attention was focused on a plate covering the film-projection of the driver- and control module belonging to the beautiful AS 60 transmitter, in the Swiss Army formerly known as M1K.

Let us first consider the left-hand side of this plug-in stage


What can we find under the sloping black plate?


Plate being removed and viewing the prism and the projection mirror opposite the frosted glass window


As to understand what this is about:


The yellow ray is leaving the microfilm arrangement on the left-hand side

Ending up at the rear-side of the frosted-glass projection window like is shown below


The scale is actually projected from a microfilm glass disk


  Viewing the cover of the microfilm compartment.

Please notice that the cover in this case is not black but having aluminium paint; this photo taken from a different unit employed in my private transmitter.

The two ceramic tubes just covered by a vertical mounted RF choke are special types. Inside having two ceramic capacitors one with a positive and the other one with a negative temperature coefficient. This latter arrangement should compensate the overall stability of the transmitter frequency.


Viewing the controls at the front-panel

This transmitter can be 'keyed' of course by means of a normal Morse key, but also by means of a telephone signal from distance. For it it provide the option with an external 'tone' signal or using the internal 'tone' generator signal. The latter allowing minimal load of sensitive keying circuits.

Finally viewing the transmitter from:


The right-hand side


Viewing it from the left-hand side

On the left the oscillator coil being made visible because we replaced the heavy screening plate by a Perspex (Plexiglas) window

For those interested in other aspects of this wonderful stage please earlier AS 60 (M1K) webpage


Why not investigating what is inside the die-cast box?


Cover plate being demounted

Up we notice the projection lamp and the a bit fuzzy a mirror at 45°.


The seemingly transparent glass disk is actually carrying the microfilmed frequency scale information 


On the left the light rays leaving the projection lamp passing first: - through a lens - then being deflected 90 degrees by means of a 45° mirror - then passing a quite miniature lens (both lens positions are slightly moved up or down for the appropriate frequency band) - the light rays crossing the glass disk carrying the microfilmed frequency information - then after passing the second small lens - being reflected inside a prism towards a projection mirror (placed under an angle such that the light rays do not interfere with the prism body)- eventually projected at the frosted glass window shown below


The for its days very exceptional frequency scale reading



The projection lamp being tilted which normally is just in front of the first lens


The projection lamp-holder put in its operational position


Having previously discussed the implementation of a dual capacitor inside the ceramic tubular capacitors. C 10 was once replaced from one of the AS60 module we possess. Its capacity is given: 100 pF with a tolerance of +/- 0.5%


This arrangement consist of two circular capacitors

The outer green colour capacitor having a positive coefficient, whilst the inner red circular tube is a negative Tc.

Theoretically it is even possible to provide a completely neutral capacity behaviour; I guess that this wasn't the case here. The entire arrangement is regularly kept within a hermetically sealed-off environment.

You hardly will find anywhere else in the world (1940-1945) such high quality capacitors. Its manufacturer was Hescho, then the world leader in this field!    


To be continued in due course


By Arthur O. Bauer