The following links will hopefully help to gather further information about communication equipment. We can however not influence the contents of these web pages and therefore we can not be made responsible for the contents.
The ALGRA Funkarchiv is a good source for manuals. But one must be prepared to wait quite a long time for the delivery. Web pages in German.
The "Boatanchor Manual Archiv" is a valuable source for (free) scanned boatanchor manuals.
Burkhard Baumgartner has a wonderful collection of German equipment from Rohde&Schwarz, Siemens and Telefunken.
Martin Boesch has prepared some very good information about communications receivers. The German companies Siemens, Rohde&Schwarz and RFT are covered. Web pages in German.
Heinrich Busch has collected photos and technical information for quite a lot of communications receivers. The emphasis is on "Seefunk-Empfaenger" i.e. receivers used on vessels. Web pages in German.
A lot of documentation (manuals etc) for German WWII communication equipment can be ordered from Werner Gierlach. Web pages in German.
Homepage of the "Gesellschaft der Freunde der Geschichte des Funkwesens". Web pages in German.
Nice photos and data of various receivers. Web pages in German.
Many pictures of mostly German equipment used in military surveillance. Look under the headings "MgS FmBer92" and "Info Box / Live" for the photos. Web pages in German.