On Wednesday, January 22, 2003 at 9:45:02 AM UTC+11, Mel3k wrote:
I'm not sure if this has been asked before, but why does AM radio in
Europe/Asia tune in 9khz steps while North American AM goes by steps
of 10khz? Also, why did some countries like Australia switch from
10khz to 9khz steps some years back?

Thanks for your insights

If you go back to the history of AM radio, the entire world was using 10 kH
z on AM, which was back in the days when the radios did not have digital di
splays on them. It was one of those old radios in which you had to fiddle w
ith the dial to find a particular station. In those days it was necessary b
ecause it required a much wider spacing. When they started making radios wi
th digital displays on them, that was when Australia, New Zealand, Asia, Af
rica and Europe began the switch-over to 9 kHz spacing. The purpose of swit
ching to 9 kHz on AM was to accommodate more stations in. For some reason N
orth, Central and South America was still stuck with 10 kHz, and I believe
it's because although they started making radios with digital displays, the
frequencies are still based on the old radios which had the tuning dial. P
robably another reason is because there were already too many stations on t
he AM band that it was not convenient to narrow the bandwidth from 10 kHz t
o 9 kHz. Plus back in the early 80's they had plans to switch to 9 kHz like
the rest of the world, but the changeover never really worked. These days
there are some American radios which allow you to switch between 9 kHz and
10 kHz simultaneously, in the likely event that the Americas made the trans
ition to 9 kHz spacing. I hope that answers your question.

On 11/12/15 19:19, wrote:
On Wednesday, January 22, 2003 at 9:45:02 AM UTC+11, Mel3k wrote:
I'm not sure if this has been asked before, but why does AM radio in
Europe/Asia tune in 9khz steps while North American AM goes by steps
of 10khz? Also, why did some countries like Australia switch from
10khz to 9khz steps some years back?

Thanks for your insights

If you go back to the history of AM radio, the entire world was using 10 kH
z on AM, which was back in the days when the radios did not have digital di
splays on them.

Europe used 9 kHz spacing for most of the band, and 8 kHz for the top
end. In 1978 the switch was made to 9 kHz only, and in frequencies
dividable by 9. So there is no relation to the invention of digital
displays. The US not only has 10 kHz spacing, stations used up to 10 kHz
in their modulation while European stations used only 4.5 kHz. So in the
US 'neighboring' stations had to be separated geographically.

gr, hwh