[AMRadio] The zeal to eliminate AM mode on the amateur bands.


Donald Chester k4kyv at hotmail.com
Mon Sep 19 17:45:21 EDT 2005




>Hmmmm - I thought SSB was developed by the telephone
>companies or the military back in the 1930s, rather than by
>AM ham ops.
>
>Maybe I was given wrong information.

Actually it was before 1920, for transatlantic communication on longwave.  
To get any kind of efficency at all out of the antennas for those 
frequencies, the tuned circuit had to be so high Q that the bandwidth of the 
antenna was too narrow to allow a full double sideband signal to pass, so 
someone at Bell Labs figured out that all the information could be 
transmitted on one sideband.

I have seen circuit diagrams for balanced modulators in pre-1920 radio 
books.  The SSB signal was basically generated with a balanced modulator and 
the antenna itself served as the sideband filter.

I think the intended meaning of the message is that it was AM hams who first 
investigated using SSB on the ham bands and shortwave.  There was a short 
article on SSB in the mid 1930's in QST, with the promise of more articles 
to come on practical construction.  That article was mysteriously cut in mid 
paragraph, and nothing more was heard of it, nore were there any subsequent 
followups.  SSB began to be developed for HF on the ham bands just after 
WW2.





More information about the AMRadio mailing list

This page last updated 13 Dec 2017.