The PF86 Tube
For both the Regensburg and the Notre Dame microphones Cathedral pipes uses a Old Stock PF86 vacuum tube. We have over 2000 of these in various classic brands... Or so we thought! As it turns out no matter what brand is stamped on the PF86 it is the code on the tube that tells the true story. Ours and we are guessing all NOS PF86 tubes are stamped with the two letters Dk then a digit. The letters tell us they all came from a well-known factory in Hamburg Germany owned by Valvo/Phillips. The digit indicates which year within the 1950s the tubes were made. Ours so far are all between 1953 and 1958. So, no matter what the box or label indicates they are all in fact the same...
Valvo/Phillips GmbH circa 1950
Before 1914 the company "C.H.F. Mueller GmbH Hamburg" produced only X-ray tubes (therefore, they were known as "Roentgen-Mueller") after 1916, probably triggered by the requirements of WW-I, "ordinary" tubes, mainly transmitting ones, were added to the program.
Then in April 1924 Just before broadcast radio took hold in Germany Mueller spun off the transmitting tubes group into a daughter-firm called "Radio-Roehren- Fabrik GmbH" or just "RRF GmbH" (meaning radio-tube factory); they took over the tube-production from Mueller.
In 1926 RRF was renamed to "VALVO". that name was inspired by the latin word "valvae" (something like door wing, to symbolize the flow-control of electrons), plus the English "valve". since then VALVO used their typical logo, a sort of jagged ring with a stylized "VALVO" written inside, which was kept (almost) unchanged for more than 5 decades.
In 1927 Philips bought C.H.F. Mueller (Mueller had financial problems), and later in 1932 also VALVO (Mullard became a Philips-daughter, too). The tube production was then moved to Hamburg-Lokstedt. Once moved bigger and modern factory buildings were erected for the manufacture of electron tubes.
Over the next 50 years Valvo-Phillips Hamburg grew to four separate sites and 8000 employees. Manufacturing every electronic component imaginable at that time. The Original tube factory location Hamburg-Lokstedt pioneered the manufacturing of the first transistors and then semiconductors and integrated circuits. They were also responsible for large improvements in color television CRT tube designs and reliability.
The decline of the European component industry, and thus also of Valvo began in the '80s with the rise of industry in Japan. The Hamburg factories became unprofitable and massive restructuring took place and large business units were sold off. In 1988 Valvo-Hamburg was sucked back into the parent company Phillips and continued its semiconductor activities.
In 2006, the former Valvo semiconductor activities of Philips spun off and now operate under the name NXP (Next eXPerience) and continues in Hamburg at the same location today.
22529 Hamburg (Lokstedt), Stresemannallee 101
NXP (Next eXPerience) circa 2012