Prototype set is here

[colortel]

To the Color Gang,

Nick and I have just had a wonderful 1 1/2 hours on the phone tracing his chassis circuits from the CRT grids back through the 6BL7 color crt drivers,and 6AS6 demodulators. We had discussed the evolution of NTSC standards, back through the Feb. 2, 1953 NTSC Field Test Specification, and further back to the initial definition of the NTSC field test standard published on November 26, 1951. See http://novia.net/~ereitan/NTSC_overview.html

This November 26, 1951 standard used quadrature modulation of 1 MHz. B-Y and R-Y color difference signals, CPA (Color Phase Alteration), a 3.898125 MHz. subcarrier, and reference burst on a pedestal on the back porch of horizontal blanking. . In doing our tracing Nick discovered a transformer labeled "CPA".

Our initial conclusion is that it is a chassis probably used during the CPA Field Testing during 1952. There were several manufacturers who built field test receivers during that period.

We have yet found nothing to confirm that it was built by RCA or by any other manufacturer.

The chassis may have been modified from CPA up to the later NTSC Feb. 2, 1953 standard. We will see.

Further tracing of the circuit and documenting the circuits will be don.

Ed Reitan