On 15 December 2015

New photos being implemented, showing what was found inside this neat module.

These photos have been added at the end of the main chapter.



Empfängerprüfer für Torn. Fu. bf*

Frequenz 3050 kHz


This latter information might point at a quite low serial number. Also the occasions that I have encountered this device are most rare. We may thus think of a rather small number of sets have been once made. 

/43 stood for 1943

What might have been the case too, is that we possess a fragment of it showing apparently that 'zinc-pest' caused early deterioration of the device. Such occasion always point that likely this did happen more frequently.

Whatever the case, rare it is.  




Direved from:


* We find, that the receiver spectrum is equal to Torn Fu b1






3.0 – 5.0

3.0 – 6.66


1.5 – 2.3

1.5 – 2.6


4.5 – 6.66

3.0 – 6.66


We have some years ago dedicated some space to this intriguing device

This occasion is nevertheless a good opportunity to catch someone's attention again.



The set is rather easy to operate

Disconnect the power cable and remove the headphone plugged into the most left-hand two pin headphone plug. 




1)    Empfängerprüfer nach neben stehendem Bild anschließen. Antenne - Wahlschalter auf "Stab Ant" Funkgerät einschalten, Betriebsspannungen überprüfen, 1½ Minute warten.

2)    Empfängerempfindlichkeits-Prüfung bis zum Anschlag drücken und drehen.

    a)    Geldstück in den Schlitz der HF-Einstellung bis Instrumentzeiger auf grünen Strich ausschlägt.

    b)    Lautstärkeregler am Funkgerät auf mittlere Lautstärke im Tg-Bereich stellen.

    c)    Frequenzeinstellung des Empfängers bei angegebener Frequenz hin- und herdrehen bis Instrument lautesten Überlagerungston anzeigt, Ausschlag mit Lautstärkeregler auf grünen Strich einregeln.

    d)    Frequenz-Einstellung um fünf Teilstriche verstellen, Instrument muß jetzt Restrauschen innerhalb des blauen Sektors anzeigen, dann Empfindlichkeit ausreichend.

    e)    Wenn grüner Strich nach c) nicht erreichbar ist oder wenn Restrauschen nach d) blauen Sektor übersteigt, ist Empfänger nicht genügend empfindlich. Röhre auswechseln, Prüfung wiederholen.

3)    Empfänger-Frequenzprüfung:

Wenn Überlagerungston nach 2c) mehr als +/- 1 Teilstrich von der angegebenen Frequenz entferntliegt, ist Eichung nicht mehr genügend genau.

4)    Senderleistungs-Prüfung:

Beliebige Sendefrequenz einstellen, Taste drücken, Ant.-Abstimmung auf Größtwert des Antennenstromes einstellen. Strom muß dann mindestens 80 mA betragen.

5)    Sender-Frequenzprüfung:

Vergl. Merkblatt D 940/5 und Gerätebeschreibung (D 940/3 für b1, D 940/4 für f) des Funkgerätes.

6)    Nach Gebrauch Batteriekabel vom Empfängerprüfer entfernen, da sonst Verbrauch der Batterien.



This photo may explain the way the test set being attached onto the Torn Fu b1 or f

From the previous text we learn that this set was meant for calibrating the receiver scale at 3050 kHz, though, it could also check whether the transmitter is providing sufficient antenna power.



The left-hand side connector replaces the power cable which is now plugged-in on the left-hand side of this neat module. On the right-hand side we see two contact pins which make automatically contact with the headphone connection of the Torn Fu b1 or f set  



This photo may explain how the module is to be attached



Difficult to show within a brief photo series, is the way this intriguing device being kept when it is to be stored as an auxiliary test set



When the antenna cable being placed as is shown, the outside plate can be folded around the centre module, forming a compact device




With a different photo of the module being attached onto our Torn Fu b1

The way the antenna cable and the earth connection being made is quite clear. Albeit, that our antenna switch is apparently set wrongly at: Draht-Antenne 



on 15 December 2015


Photos have been taken and I would like to share these with you:


Starting with opening this magic module

We have not yet found a genuine documentation to it.


Quite some can be learned from viewing this photo

The broken glass envelope is a diode of the series SA 100 - SA 102. Its real type number cannot be noticed - as it is from outside not visible.

The module being manufactured by Mende in Dresden.

The Al tubular housing shown next, on the left-hand side, is from the moving-coil meter attached onto the opposite (front) panel.

I guess, the coil designated L is the oscillator coil.


Viewing it from the opposite side

J is the moving-coil instrument.

The coil on the left-hand side designated D that points into the direction of a so-called Drossel or choke. W 11 is a wire-wound pre-set potentiometer.

Strange is - that what is designated D is tuneable.

Quite mysterious is the orange transformer of the right-hand side.

The symbol what might look like an Ü is the symbol for a dust-core transformer (Übertrager).

In contrast to what I did expect, there isn't a quartz involved.


1275 3? is a part of the number on the dust core transformer

I doubt - that these indicate coil winding numbers!


Viewing it from a different perspective


Zn die cast box lid, likely lot number 520

Please notice the groves which counter-fit to the main chassis, as to screen off better.

The rectangular box or part contains the module lock.


Before closing this module I would like to know what value have been used; it was a special triode for VHF application type SD1A


Viewing from a bit different perspective

You may wonder why they have used such VHF valve type whilst its application here was about 3 - 4 MHz?

My guess, the Mende Company manufactured also a module having comparable application of receiver test set but now to the Torn Fu d2. It has to be noticed though, this module was more or less mirror like constructed, because its power plug was just on the opposite of the transceiver. Thus the power plug was, when being mounted, coming out on the right-hand side.  


I must admit, that I don't feel myself obliged to dedicate much time in determining its integral schematic. Its compactness simply is too dense.



By Arthur O. Bauer


Please notice also the: Torn Fu b1 and f, antenna-tuner for application in a bunker