Excerpted from a private email with Italian Engineer Emilio  Ciardiello .


Date: Sat, 11 Apr 2009 16:30

To: Joe Sousa 

From: emilio ciardiello 

Dear Joe,


I gave a look to the excellent job you did to preserve the Philbrick Research fame. Looking at the exhibits, I went back some 40 years when, still a young student, I saw my early P2A amplifiers, servicing some Boonton automatic bridges.


About the P2A Philbrick amplifier, please feel free to use the information as you want. Unfortunately I have just a faded memory of those Boonton bridges, no model and no picture. I just remember of them for their excellent quality.  I remember three rack modules for each bridge. The seven reference resistor decades inside the bigger unit were from ESI, Electro Scientific Industries, accurate to 0.01%. The P2A was chopper stabilized. I handled them around 1968 or 1969, but the manufacturing had to be dated at last 5 years before. Inside the control unit there were a lot of 2N404 germanium transistor used in RTL logic. I remember that I tried to reach the manufacturer but it was no longer active; hence I asked for advice my lecturer of Electronic Measurements in the local Polytechnic.