Nachtfee acryl substitute aircraft display
a new endeavour
on 5 June 2023
Current status: 16 September 2023
Part 6 Nachtfee Console transformer substitute and replacement extra page
This project runs already since September 2021.
We inherited a circular cathode ray yoke concept, which is especially built for the German Air Force (Luftwaffe) type LB 2
I first took a brief serie of photos, maybe not in an optimal setting, but I prefer to consider it as a kind of tantaliser.
Viewing it as our device did arrive
Viewing it from its right-hand side
Please bear in mind, this is only a concept of combining our foregoing experimental construction and what it once might have, more or less, looked a like
Maybe you now understand that some similarity exists between photo 2 and the above wartime drawing
Most likely drawn by a capture German PoW.
It took us quite some time before we got a substitute aircraft display operating.
Viewing the acryl display substitute from a different perspective
Our next endeavour should, of course, be mounting the components
This will, Deo volente, being accomplished on an acryl, more or less, square base-plate; however, the screw-holes should be accomplished by an expert, as acryl is sometimes a tricky material in respect to drill holes.
Viewing it differently as to allow a more complete impression
The darker sections at the phosphoric screen must originate from some reflections; as these aren't shown on the forgoing photograph
It truly has become an elaborate acryl construction
The tooth-wheel accessible on the top provides the possibility to adjust the the North signal (timing 0° marker) yoke - against the North line engraved on the LB2 crt display correctly
What a magic impression isn't it?
The two holes allow us to access the 2 RV12P2000 valves in this context both acting a video-clamping diodes which after all perform better than semi-conductor does
Marvellous, in my perception
The two circular holes are for keeping the RV12P2000 base-sockets
This connector was a quite standard GAF connector, designed by Tuchel, which company became in the 1950s Amphenol (also known as List-Stecker)
In the 1960s and 70s maybe 80s Amphenol edge-connectors employed in combination with flat-cable constituted versatile- and a reliable product;
but its basic concept was German. It was after the war widely copied in France as well as Russia.
In 1999 we visited Vietnam and were walking in the streets of Saigon. Someone set down and was dismantling an electrical unit and I saw some components quite familiar to me. It proved to be a "Chinese" copy, but Russian made of the German wartime type, and completely exchangeable! The only difference was, that the Russians used soldering tags whereas the Germans used screwing connections (as were the French post-war copies.
Viewing the former situation a bit differently
Viewing the last picture of today a bit more exposed
The new display is now approached to get the foregoing electrically situation reconstructed
As to protect the "virgin like" Nachtfee air-display and facilitating or next series of experiments, Hans touches it with wearing silk gloves
Fore the foregoing reason, as to make life easier, Hans wounded the acryl body in a soft paper strip
Our next move was to rewire the foregoing circuitry but now re-wiring it onto the presently newly mounted LB 2 CRT
As to modify its circuitry, we had to take into account to change, in particular the injection of the "Video" signal
First Hans had to re-discover the actual LB2 CRT contacts
Peter Kievits gave me some time ago, the schematic copies of the Nachtfee display (Console)
I already knew that the way the circular Nachtfee LB 2 presentations was commenced was very favourably, compared with out foregoing way of presentation.
Essential firstly was, to establish the state of affairs before we dismantled the foregoing setup
Fore it we first had to restart our Nachtfee console, which caused some problems; viewing backwards, we encountered already in the passed a mall function of the console time-base deflection system
I must admit, that I don't know exactly yet what is mall-functioning, but at least I know that it concerns Rö 8 (EF 14); maybe the parallel capacitor parallel onto its deflection output transformer. Its circuitry is very difficult to access.
However, it operates currently fine
When this stage fails, the HT at the EF 14 anode remains about 360 V, but no signal being provided.
The 1:10 prove is still connected onto the Rö 8 anode and the meter in the background is indication the voltage across the EF 14 cathode resistor
This experimental session will now be closed, and we would like to introduce a for us new technology as being used inside the Nachtfee console
Using experimentally the circuitry as is maintained in the Nachtfee console; but because no values being provided, we considered the Lichtenstein FuG 202bc circuitry, as for the latter we possess indication of the variable tuning capacitors.
The two tuning capacitors are according to the FuG 202 bc schematic, facing the G1 ca. 40 - 5000 pF and the one connected onto the deflection cylinder ca. 2000 pF (our capacitors are providing a wider capacitance range, but both allow well adjustments within their mutual tuning ranges)
(Thank you Peter Kievits)
We disconnected the clamping circuitry as well as the high-lighting (brightening) circuitry; but adopted two variable capacitors of German origine
And, we were astonished how well it works, and making the brightening circuitry redundant.
The crux is - to supply the video - pulse at the same time, onto the g1 as well onto the circular deflection cylinder; it has to be find out the amount of signal ratios between G1 and the circular deflection cylinder.
We encountered a wonderful video presentation, making external brightening signals redundant
(3) (since 3 July 2023)
On a rally on 24th June I obtained among other things a new type of mica trimmer condensers, which might fitting better in our modified system concept
Each box contains a mica trimmer tuneable between ca. 30 - 4000 pF
Once manufactured by Siemens.
The blue series capacitor is only implemented for safety precautions as on the left-hand device onside is directly connected onto ca. 2 kV; albeit that the current has been limited by means of a 1 MΩ resistor, thus maximally resulting in ca. 2 mA current.
The metal cover is insulated from what is inside.
We tested it wired inside our existing experimental (pertinax/phenol) mounting strip
The small board in front constitute 10 zener-diodes in series which are being fed via the fore called 1 MΩ resistor reducing 2.3 kV HT to ca. 2 kV HT fed onto the circular deflection cylinder of the LB 2 crt
It proved necessary to stabilise the crt HT as the the brightness control was, otherwise, too much blurring the painted signals.
It seems that we can integrate both Siemens trimmers inside our new acryl display
The modification drawn by means of a pencil into our first concept schematic
The idea matured by studying the way the Nachtfee Consol provisions
The crux seemingly is tuning the injection-voltages onto both the g1 (= Wehnelt cylinder) as well as onto the deflection-cylinder of our circular LB2 crt
What we couldn't manage with the two forgoing mica trimmers, is now quite simple to manage with the two Siemens trimmer.
There clearly exists a particular ratio setting between the two video signals fed onto g1 as well as the anode cylinder.
I suppose this is being caused by the slope curve of the signal fed onto the g1 and the voltage fed onto the anode cylinder.
Viewing it from a slightly different perspective
Visible is the aircraft simulated display, but truly showing the actual 0° phase of the Nachtfee aircraft time-base
Used to indicate on the Nachtfee control-screen the actual status of the air-craft time-base reference.
This pulse is essential as by means of this reference the console operator can adjust the signal phase transmitted towards the aircraft transponder.
As to guarantee that the Nachtfee order arrives just at the correct instant at the aircraft display, the Nachtfee signal has to be phase shifted correctly. Hence, the Nachtfee consol needs therefore to know what the actual status of the aircraft time-base is
For a full explanation - please consider my: https://www.cdvandt.org/nachtfee-v6-mp4.htm
Showing the the current test set-up
(4) (since 30 August 2023)
Hans Goulooze has during the summer period prepared provisions for our Nachtfee aircraft display reconstruction.
We have two major concerns: the layout and its realisation should be sound.
Though, the components should be arranged and mounted logically, and the cabling should be wired optimally.
Soldering, when the acryl, or whatever mounting carrier-plate, is attached is to be prevented.
This essential plate is to be used for exact positioning of the drilling-holes
Designing a circuitry fitting together is demanding special skill
It looks all quite simple, but it necessitates a sound dimensional skill
The next step is mounting the partly wired circuitry exactly on top of the drilled holes of, ca. 3.1 mm
When you view this photo carefully you might notice the slight transparency difference of the acryl or polycarbonate mounting (montage) plate.
Viewing our mounting plate from its bottom-side; the 3 mm screws will be tooled in the reconstruction of our acryl aircraft display frame
Please notice the schematic of the LB 2 circular deflection crt on the far right-hand side.
What Hans designate Empfänger line, actually is the video signal
Viewing the mounting plate from the top position.
The cables pointing towards us, being connected onto the LB2 base
Whereas the to cables point upwards being meant for the two controls for:
control at the tiny front panel
The spacing of components looks like a bit too roomy, but please bear in mind that at some lines we encounter ca. 2 kV anode voltage fed onto the circular deflection cylinder.
The LB 2 CRT internal connections are partly visible on the right-hand side of the contact-strip. This crt is provided with a circular deflection yoke system.
(5) (since 8 September 2023)
On 7 September 2023, Hans Goulooze continued with preparing the future wiring of our Nachtfee acryl prototype
The purpose of this current contribution is - to show you the progress Hans Goulooze's commitment is making
Very important is to approach this beautiful acryl display soundly, as to prevent for un-necessary damage.
Even minor mistakes cannot be corrected afterwards.
Viewing the right-hand side of our future aircraft display construction
Viewing the acryl display construction from different sides
Moving the perspective more towards the front-panel
Considering now the left-hand display side
It proved necessary to stabilise the 2 kV high-tension, because when CRT screen brightness changed also the trace focus responded negatively
Therefore we increase the supply voltage to ca. 2.3 kV and wired in series an 1MΩ resistor, this was loaded by 10 x 200 V zener diodes. Through the 1 MΩ flows only (U = I· R) → (I = 300/106 = 300 µA); consequently through the zener diodes is flowing even less as also the LB 2 crt system circuitry is constituting a current load.
It proved to operate smoothly and
About this position we plan to fit our CRT 2 kV supply stabilisation
Considering the current working conditions; which should, Deo volente, change next weekend 9 and or 10 September, as to prepare room for our scheduled Secret Communications 4 exhibition
To be continued in due course
By Arthur O. Bauer