Joe Sousa schrieb:
Thanks for writing back.
The excellent closeup photos that were added recently were contributed by Philbrick enthusiast Achim Dassow from Switzerland. As a result of Achim's contributions, we have been having an intersesting exchange about early amplifier design for voltage regulators. I plan to edit the results of the conversation and post it.
I copied Bob Pease in case he would like to talk about the point-to-point wiring of the modular opamps. It is odd tha the lowest cost tube opamp of the Philbrick line, the K2-W, around $22, was never converted to a PCB.
*** I was never involved in the production design of the K2-W or other high-volume op-amps. I think the components were wrapped around some stainless-steel pins, soldered, and then slid off the pins, and tacked to the plug and sockets. I was never consulted. We did use PC boards in my SK2-V and -P. I don't expect to comment more later - I'm not very knowledgeable.
I have seen (nearly) verbatim copies of the K2-W in the Heathkit HR-19 5-opamp manifold, and in an ultra rare Embree module I got on ebay.