Many of the early repeaters were placed on the air by people working in two-way radio shops using surplus commercial radio equipment. One of our local long time legacy repeaters started life as a surplus Motorola Research Line tube unit. Sub Tone or CTCSS operation was added later with a bolt on chassis using the famous long copper tone reeds. I would guess that era to be sometime between 1965 and 1975 when 2m repeaters first caught on (became popular) with the general ham public.
Ham Radio Ops started adding ctcss when repeater problems required restricted operation. There are/were a number of after market ctcss generators... just thinking back about some of those boat anchor add-on tone boxes that were bigger than some of the current radios you now operate. The 555 timer chip solved a lot of the ctcss generator cost problems and we cranked out these "hummers" en masse. Three or four wires in the right place and we were off and running. A copy of that original 1970's circuit is on the sonic page. http://www.radiowrench.com/sonic/so02148.html After a decade or more of do-it yourself ctcss encoder installs, the Amateur Radio Market started placing single tone ctcss encoders into radios in the late 70's early mid 80's. Early Heathkit & KDK units come to mind as radios sold with one or more available ctcss tone frequencies available. Mid 1980's saw the migration toward multi or front panel selectable ctcss operation with less quirky designs and controls. Some time along the mid 80's hams also started using DCS (digital ctcss) in specialized aps. Many of the rural parts of the US don't use constant CTCSS repeater control. CTCSS operation is pretty much a must have in most Metro Areas. So... now ya know. cheers, s. > "larry allen" <[EMAIL PROTECTED]> wrote: > Does anyone know when subaudabe tones were introduced into ham radio > repeaters.. or more specifically when they became standard in ham > radio sets? > Larry ve3fxq
