SAQ Reception now with vintage tubes of the 20's !

May I introduce my special project, which was built in order to pay tribute to all volunteer's at the Grimetron Transmitter. Thanks for the effort made over the years to keep this piece of World Heritage alive!
Special, because the described receiver comprises only tubes used in those day's of the 20s. And, if you look at the operator's desk, one will find a genuine Telegraph displayed. It was my intention to record the messages on paper too. Unfortunately, I didn't succeed to get one of my own.... In the meantime, the dot's and dashes are reproduced by a buzzer (beeper).
Functional description
The transmissions from SAQ are in CW. To get an audible signal, a single tube (RE084) oscillator (BFO) which heterodyne the 17.2 kHz with a frequency 500 Hz higher or lower. It is loose coupled to the main tank.
The receiver itself is a TRF type, without reaction!
A vintage Loewe 3NF tube (anno 1926) is in use. Often called the 'First Integrated Circuit” because they managed to put three triodes, together with the necessary capacitors and resistors, in one bulb!
Triode one acts as an anode bend detector without reaction. The followings two triodes amplifies the derived 500 Hz.
An also vintage Horn Speaker is driven by a penthode (RES164). The L/C circuit (tuned to 500 Hz) at the steering grid gives me a better selectivity.
Finally at the right, we see an additional Relay-Unit, meant to drive the Telegraph. After amplification in a triode (RE034), the audio signal has to pass another lf filter which can be carefully tuned in the range from 400 to 600 Hz. Also important is the correct adjustment of the threshold voltage at which point the special Telegraph Relay will come on. This is done by varying the bias voltage of the relay driver triode (RE134).
In this video you hear a clear tone, produced by the temporarily installed buzzer. Sometimes atmospheric discharges or fading will produce false outputs. What's more, this morning transmission was weak in respect of signal (plus noise) against noise relationship at my QTH nr Maastricht.
The antennea is a 12 meter wire under the roof.
Wolfgang Holtmann, PA0FTF