Repair-day of German apparatus (1920 - 1950)

On 12 November 2011 we have held our first repair day

 A day for both SRS and NVHR members.

Although, everybody else was also welcome.


We knew from the very beginning, that this would be an experiment.

The first visitors turned up about 10 o'clock. Among them the Foundation Board members Marc and Paul, who very kindly brought along a very heavy crate weighting >95 kg. It contained the long awaited Nachtfee apparatus, which is now under investigations. It proved however, that amongst the early visitors no one had brought a set which we could investigate. Giving me some time spending with dismantling the Nachfee frame plate-covers. I was really surprised by its complexity. Far more than was expected!


The photos have kindly been provided by Anton Kroes.


The first set under considerations was a Swiss E39 receiver made by Autophon. A nice but mechanically far too complicated. According Jan Wolthuis the set had a failing BFO. My opinion of the mechanical design is, that such a set was designed by a company used to develop machineries, and now had the task making a communication receiver. Its construction electrically is certainly sound, but its designer might never have considered that something could fail. In this respect it is a misconception. Having encountered this aspect, I decided to cancel this repair, and it has to wait for a better opportunity.


Antoon Steenbakkers asked me whether I could take a look at his two Feldfernschreiber (Feldhellschreibers)?


I honestly had to admit that I never have seen Hellschreibers in such a bad shape! Both sets were failing completely albeit, in different respects


However, it was not before Ton Buitenhuis arrived with under his arm a chassis-frame of a Torn Fu-b1 that the real thrill started.

Lacking its case, wondering whether the set was worth spending time on it. Is it possible that someone can have a look at it?


The Torn Fu-b1 under investigation

The box in front belongs to Hans Muijser (in the blue shirt), and which contains a set of batteries, one supplying 2 volts and one providing HT of 135 volts (and also one for negative grid supply). 135 V I believe is a bit much, but have to check if I am right.

The set did respond interruptedly in first instance. Mainly due to switch-contacts which were failing owing to various kinds of oxidation.


Those familiar with fault-tracing, will understand the over-kill of measurement apparatus


For measuring the filament supply (2 V) one must have some chopstick experience!


The indicated voltage is 64.3 volts, this is not what I measured in the previous photo!


Ton Buitenhuis (grey shirt) is following the progress


Whatever one may think, they were very concentrated (dedicated) watching what the experiment was bringing


Without further comment



Although, the challenge was only Ton's Torn Fu b1, the other side was, that we could spend some hours in making his set workable. It must be said though, Ton Buitenhuis must clean all the contacts and he has to find out why the transmitter worked only in a part of the frequency range. Maybe caused by someone who might have changed the setting of the gear-wheels which links the driver as well as PA stage. For a dedicated radio amateur (PA 0 RTB) this must not be a "mission impossible". But it is not the aim of our Reparatiedag (Repair-day) to repair every aspect of a set.




Please go back to, or proceed with: Agenda and reflections