I will keep an eye out for any additional information/articles about those transmitters in the newer issues. Right now I have moved back to the 1930 era
Glenn H. Browning and James Millen have an interesting article in August 1930 with the title, "Satisfying the Demands for Sensitivity, Selectivity, and Quality in the Design of a Modern R.F. Tuner". The title length reminds me of some of the Ph.D. dissertations I have read and all it is missing is the requisite colon and sub-title. It looks like this article provides the background for the SW-5 "Thrill Box".
In February of 1931 we have "Dr. Robinson Explains the Stenode Radiostat" which must be one of the earliest examples of a crystal filter used in a receiver. It has a 100 Khz. IF with the crystal installed in the final IF stage.
I will try to scan these later this week.