One Evening On 75 Meter Amateur Amplitude Modulation

A few words about the 30K series. I have been a Collins fan since I was first licensed in the 1990s, but really fell in love with the 30K when I visited the home of a fellow amateur. He had the commercial version of the 30K-1, known as a 30K-5, and I was privileged to work on it for him last December. Very similar in design, the 30K-4 and 5 are commercial models offering two discreet tank circuits for rapid frequency changes but lack the bandswitching arrangement of the 30K-1.
The 30K series was designed by Collins engineer Warren Bruene in 1945 and was first offered for sale the following year. It was, in some way, a “Hail Mary Pass” for Collins as the war contacts were drying up, and yet amateur radio operation was still banned during wartime. Collins forecast a pent up demand from the return of GIs from the war, and with the elimination of the wartime ban on amateur operation, hoped the 30K would fill the gap.
Sales were somewhat limited as the 1946 cost of the 30K-1 transmitter and 310A exciter was $1450, the equivalent to approximately $15,000 in today’s dollars. According to Jay Miller’s, KK5IM, excellent publication, “The Pocket Guide to Collins Amateur Radio Equipment 1946-1980”, less than 100 of the 30K-1 are known to have been built, and few survive today, making serial number 32 a rare bird indeed.
Visually, the 30K transmitter series are most impressive to behold, housed in a cabinet 5 ½ feet tall, finished in black wrinkle paint, and weighing over 350lbs, this is a big transmitter! The design of the unit is pure art deco; vertical and horizontal chrome accent strips, a large window for viewing the 4-125 final tube, and a most impressive meter panel at the top of the cabinet, also housed behind glass.
Looking every inch a serious transmitter, the 30K-1 is of robust construction along the lines of commercial broadcast gear. Emission modes are CW and Fone (AM), with the plate input power given as 500 watts on CW, and 375 watts on AM. The 30K-1 offered coverage from 80 to 10 meters using two plug-in output coils. With a tube compliment of 11 tubes in the transmitter, and 10 tubes in the 310A exciter, the 30K station as much a delight to operate, as it is to look at.