Überlagerer Typ Ln 20240
Status: 3 October 2016
The astonishing complex LO originally scheduled once for the Würzbug systems.
However, after the Bruneval raid on 28 February 1942, known as Operation Biting, this essential device fell, among other devices, in British hands.
Viewing the Ü 62 module from inside
The two different green colours indicate their particular temperature coefficient
Please look at the pair of silvered ceramic strips, where most outside being designated B (please notice explanations below)
One thing is evident, this isn't constituting a regular oscillator construction.
Its rigid construction should have constituted an unpresented example of solid oscillator design and according frequency stability.
When we consider the genuine Würzburg type A frequency scheduled for, say, 556 MHz and taking into account an IF of 25 MHz, they should have needed a LO signal at 531 MHz. However, for practical reason they operated the second harmonic - hence, 531 : 2 = 265.5 MHz.
Genuinely, they considered this frequency like a "Reichswürzburgfrequenz". I have to admit, that I guess it once might have been considered this way. (following their way of approaching these kind of matters, like there also existed a: "Reichsjägerfrequenz" and that like)
We don't need to have comprehensive imagination, to understand that there is lacking a tuning provision
The Germans were quite shocked after this event and had to anticipate (responding) as fast as possible.
They therefore first had to redesign the existing module, as to allow some sort of frequency change. Their first move was to initiate an operation providing all radar systems in existence should be provided with a selection of wave band spectra, also known as: Wismar.
The genuine (Wurzburg) frequency became got designation Welle A.
The first introduced new spectrum was known as Welle B at about 10 to 15 MHz lower
Our module being set for Welle A
They finally adopted 4 bands (ranges). Where Welle C was just below 500 MHz and Welle D just below 580 MHz (thus higher than their regular Welle A of, say, 556 MHz). Welle D just set where the efficiency of the LS 180 transmitter (oscillator) tube dropped considerably.
Please bear in mind, all had been desperate moves as to escape being jammed.
Please notice, that the genuine application of such inflexible device constituted a misconception of the highest order!
However, changing band took, according in formation, about 45 minutes. Not very convenient, but at least there existed an opportunity to employ it.
The soup was consumed hot, because, what the Germans expect might occur soon, was generally delayed for more than over a year!
Britain's real move was "Operation Gomorrah" the devastating attack on Hamburg on 24 July 1943!
Where the Germans were not only jammed electrically, but by means of Britain's secret weapon "window" as well; nowadays known as "chaff".
The latter facility still within the military ECM package, protecting aircraft and surface ships.
Partial schematic according F 001 of the genuine Werkstattbuch section f
It became common practice to notice the available wave bands; in this case A and B
However, the British were quite astonished that they themselves were lacking equipment judging its stability; succeeding by far what was at hand in England!
Viewing it a different way
We have to bear in mind, that this module, although a bit obsolete, was quite long in service. Likely some Würzburg stations up to the final end
Of course, not where high concentrations of FLAK were engaged, because these areas were heavily jammed and the only means of surviving were the provisions of rapid wave band changes.
Viewing the LD 5 doubler stage
A typical example of German sound construction
The Germans sometimes used the expression for something that is a pleasure for your eyes: Augenweide
Just it truly is!
Who designed once this beautiful module?
I simply don't know.
But, it might have been Hescho, once world's leading company in the field of ceramics.
If this being true, then likely in close cooperation with Telefunken engineers.
Albeit, that I cannot remember having seen a comparable Telefunken construction - where at least a tiny glimpse is comparable.
For those interested in the resulting British TRE report:
T.R.E (TRE) Bruneval Report No. 6/R/25 FINAL TECHNICAL REPORT ON THE GERMAN RDF EQUIPMENT CAPTURED AT BRUNEVAL ON 28TH FEBRUARY 1942
By Arthur O. Bauer
Please consider also: Werkstattbuch FuSE 62 und FuSE 65