Thanks once again. This is all good information.
Siegfried wrote:......It seems the German Navy began introducing Hohetenweil radars around 1943 or 44. This amazing companies anode modulated 50cm radars produced 50kW pulses from a single tube that could be compared to UK Navy type 284. Yet this companies technology was underutilised in my view for many years. Thej produced a range of 50cm sets, including PPI sets that had more compact antena than Seetakt and were clearly suitable for search and maintiaining situational awareness and due to their small size were suitable for small ships including one PPI set that retracted into the sail of the type xxi u-boat.
Regarding Lorenz and their Hohentwiel radar. Lorenz was originally involved with GEMA in the development of Seetakt. GEMA invited Lorenz to participate because of Lorenz’s extensive experience as a military contractor. This gave Lorenz a leg up in their own radar R&D. Many of the secret patents filed by Lorenz were actually filed in behalf of GEMA and its scientists during those years.
However, once Seetakt was successfully developed the Kriegsmarine demanded that Lorenz be cut off from the KM radar projects. The German Navy saw Lorenz as a security risk because of their strong foreign associations with American corporate interests such as Bell Labs.
Lorenz then designed an aircraft tracking and flak direction radar for the Luftwaffe. It lost in competition to Wuerzburg. Lorenz persisted and designed the Hohentwiel air to surface vessel radar for the Luftwaffe completing trials in 1941.
Hohentwiel was one of the best ASV radars of WWII. Among its attributes were compact and simple design and high output power. From an airborne platform it could detect ships from 150km and detect the periscope of a submerged submarine from 6km. The airborne version used a simple form of lobe switching (pip matching) to allow blind torpedo attacks on shipping.
Hohentwiel had a power output of 50kw (30kw in airborne versions to prevent high voltage arcing at high altitude) and a 2 micro second pulse width, giving it target illumination energy of 100kw. The transmitting triodes were anode modulated with a high voltage pulse formed from a capacitor discharge being delivered to the anodes through a Balum Transformer. This limited the PRF to 50.
The KM realized by 1943 that Hohentwiel would make an excellent alternative to the U-boat mounted Seetakt derivatives (FuMO29 and FuMO30) because of its power output and overall compactness. FuMO61 (Hohentwiel U) demonstrated a 25% increase in range over comparable Seetakt models due to the greater power output. From late 43 production of FuMO30 was halted and shifted to FuMO61.
Although Hohentwiel wasn’t capable of the same precision or resolution as Seetakt it was capable of greater range than the 8kw output Seetakt models for typical ship to ship applications. Destroyers could be detected from 36km. As you point out, the accuracy and resolution were plenty good enough for general tactical use. Tirpitz was equipped with Hohentwiel K (FuMO63) in late 1943.
The application of PPI technology to Hohentwiel was the result of a renewed collaboration with GEMA. GEMA turned over the final development and production of the Drey Freya radars to Lorenz in 1942. Lorenz of course applied the PPI technology to its own Hohentwiel series of radars