Von W. Kautter
Mitteilungen aus dem Telefunken-Laboratorium
Telefunken Zeitung 18.Jahrgang, 1. November 1937
Kautter became quite well known in conjunction to the design of the Köln E52 xx quartz filter. Also being employed in the ULM E 53- and in the Main T9K39 receiver.
Its performance was exceptional for those days. In no way matched by the rather simple, and poorly performing, quartz filters used in Allied receivers, like in the HRO, also in the BC 348 and its derivates, AR88? and other receivers. This filter type was named: phasing-filter.
Kautter's filter types allowed symmetrical bandwidth tuning.
His main patent was:
Application date 21 November 1936
Granted 13 April 1939
The main trick was to tune one condenser up and the second one the exact value down (vv.)
Each band-filter section used a mutual differential capacitor-tuning (Δ C up = Δ C down)
Please notice, that C 186 and C 201 are also trimmers, which is to be adjusted individually, as to counter the parallel capacity of the quartz crystal and its attached wiring.
According the E 52 xx specification it could tune between: 200 Hz and 10 kHz bandwidth.
In those days providing a really outstanding performance.
Kautters quartz-filter application according fig. 7 was used in the Lorenz Schwabenland RX as well as in other Lorenz receivers. They might have found a way around it, as Lorenz used a tuning arrangement where an arm fit with on both ends a dust-core disk, which could rotate over some arc and providing by this means the variable coupling (one side getting more - whilst the other side providing less band-filter-coupling
Though, Lorenz used always a single quartz-filter, whilst Telefunken often used a dual quartz-filter version.
For the many years I am engaged in the history of German wartime electronics (> 44 years), I encountered only for one occasion a reference that a report on the Köln receiver is due to be published soon.
Since I have never come across such a particular report.
My personal guess, their finding might have been so striking - that nothing glorious could be compared onto. Better leaving its performance out of the scope.
For those interested in the engendering of the Köln program:
A preliminary catalogue of May 1941, meant for their future customers
Do you want to know more about the most exceptional Köln E 52 receivers, please consider then also:
Köln E 52 Krachtöter (noise limiter)
Köln E 52 microfil-glass-scale Exceptional microfilm projection scale!