domenica 26 settembre 2021

History of SSB

History of SSB
From: Scott Blixt
Date: Sat, 25 Sep 2021 21:08:31 UTC

AWA Video: SSB was Slow to Catch On as a Ham Radio Mode

Hams are often early adopters of new technology, such as FT8, but this was not the case with single sideband (SSB) amplitude modulation. First referenced in Major General George Squier's 1911 patent that had nothing to do with RF applications, SSB didn't really catch on as a popular ham radio phone mode until the 1960s.

Antique Wireless Association (AWA) museum curator Ed Gable, K2MP, recounted "The History of Single Sideband" as part of the inaugural "AWA Shares" program, presented on August 19. Gable described Squier as an "early idea man" in the history of SSB at a time when hams had hardly adopted AM inany form.

As Gable explained, John Renshaw Carson built on Squier's patents to define the principles of SSB radio transmission theory, using a balanced modulator and filters. AT&T went all in with SSB, basing its first long-haul telephone system on the technology. Its SSB voice service to Europe, which kicked off in 1923, lasted for more than 3 decades. A receiving site in Scotland took advantage of Beverage antennas put in place for the ARRL transatlantic tests.

Gable credited Robert M. Moore, W6DEI, with introducing SSB to the ham radio community, through an article in R9 Magazine in the early 1930s. The technology remained more of a curiosity, however, in part because of the Great Depression, cost, and technical difficulty. Besides, hams of that era saw no real advantage to narrowband modes, since bands were not that crowded.

The mood began to change after World War II, though. In 1948, Oswald Villard, W6QIT, engineered the airing of SSB signals via Stanford University's W6YX, re-introducing the mode to a burgeoning and more technically savvy post-war ham community that included a lot of veterans. A 1950 GE Ham News article by Don Norgaard, W2KUJ, described plans for a 5 W, three-tube SSB transmitter he dubbed "The SSB Jr."

The Central Electronics Model 20A.

Expanding on this, Central Electronics' Wes Schum, W9DYV, built the first SSB exciter, the 10A, in 1952, and it became the company's first product, spawning a series of successor products that included a VFO based on a modified BC-458 military surplus transmitter, an "SSB slicer" for receiving, and even a linear. SSB equipment was neither inexpensive nor accessible, however.

"Cheap and Easy S.S.B." by Anthony Vitale, W2EWL, which appeared in QST in 1956, spoke to hams' attitudes, helping to advance the adoption of SSB among radio amateurs. Byron Goodman, W1DX, addressed receiver improvements with his QST article, "The Product Detector."

The Collins KWM-1 is considered the first "true" transceiver, sharing receive and transmit circuitry.

In the same decade, General Curtis LeMay, K3JUY/K4RFA, promoted the advantages of SSB to the military, heralding a phase-out of AM as the dominant voice technology. Many hams were not convinced of SSB's advantages, deriding the signals as sounding like Donald Duck. Adoption didn't really take off until the Collins KWM-1 came along in 1957. It was the first SSB transceiver to share receiver and transmitter circuitry. Heathkit, Viking, and B&W produced SSB adapters for use with current AM gear.

Other manufacturers including National and Swan came along to further boost adoption of the mode, and it wasn't that many years before SSB eclipsed AM as the predominant voice mode on the HF bands.

(via Scott Blixt, Minnesota DX Club iog via WOR io group)