The AM Forum

Two transmitters from the April 1939 issue of Radio News.  There are complete construction details for the low power rig; the high power rig doesn't look like any homebrew rig I have ever run across :)

Looks like a 1939 version of the single band finals from 20 years later.  Of course, power was harder to come by in 1939.  Not like being able to get a KW with a pair of 813's with very little drive power.  Nice construction.  Fine attention to detail.  Wish I had the time and patience to do something like that.

Nice electronic keying arrangement on the KW unit described. KY21 tubes rectify and control the HV directly, very excellent! He says there is more in future articles. Maybe the other two TX will also have their special features pointed out.

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.