I succeeded in making a replica of the 402 Amroh coil.
Original Amroh 402 coil. Hard to get !
This coil is very hard to find these days. I made a replica bij using a ferrite rod with two handwind coils.
Details necessary to build the replica 402 on ferrite core
The replica 402 is located on the lefthand side of the solderingboard (attached with two tyreraps). After connecting the coil the power was switched on and after a minute there was music! Up till now I have heard 4 different Dutch broadcast stations on the medium wave. The 90 m band (where the fishermen used to communicate, long, long time ago) however does not give sounds (except for lots of noise).
Anyway I am happy with this result. While I am typing this the radio is tuned to "Radio 5, Nostalgia", on 747 kHz AM. I am curious to see if more stations (from the rest of Europe) can be detected when the sun has dissappeared.
In the evening of May 30, 2014 with a 8 meter long wire into the garden as antenna I was able to listen to 10 stations:
Dutch (4x), English (2x), French (1x), German (1x), East-European (2x). This is better than expected. I thought most of the AM broadcast stations had dissappeared. During the day only following 4 Dutch stations can be heard (even with the long wire antenna):
Radio Maria NL, 675 kHz
NPO Radio 5 Nostalgia, 747 kHz
Groot Nieuws Radio, 1008 kHz
Vahon Hindustani Radio, 1566 kHz
Sound quality is ok. Selectivity is fine. There was a small hum which I could solve by installing a 100 ohm resistor between one of the filament connections to ground. I am impressed what can be achieved with a one-tube design.
Fisherman; copied from the original "Dr. Blan" article in 1963