[Antennas] 80 m vs. 75 m

[David Kelley]

By way of further explanation, you might recall that the formula for 
wavelength in free space is lambda = c/f, where c is the speed of light in 
free space (3 x 10^8 m/s) and f is frequency in Hz.  If you do the 
calculation for 3.75 MHz (the top of the old CW sub-band in the US), you 
get 80 m.  For 4 MHz (the top of the SSB sub-band in the US), you get 75 
m.  The use of the 80 m and 75 m designations is really just a way of 
differentiating the CW and SSB sub-bands.  In the US, 80 m = CW and 75 m = SSB.

73,
Dave NB4J


At 01:19 PM 4/23/2008, you wrote:
>Hi Wayne,
>
>80m refers (informally) to the lower half of the 3.5 - 4.0 MHz band (3.5 -
>3.75 MHz). 75m refers, also informally, to the upper half (3.75 - 4.0 MHz).
>The two designations are often used interchangeably in Region 2; the band is
>not officially segmented in this way.
>
>The Region 1 allocation is 3.5 - 3.8 MHz, so European hams refer to this
>band as 80m, but not as 75m.
>
>Cheers for now, 73,
>Adam VA7OJ/AB4OJ
>
>
>-----Original Message-----
>From: antennas-bounces at mailman.qth.net
>[mailto:antennas-bounces at mailman.qth.net] On Behalf Of DW Holtman
>Sent: 23-Apr-08 06:35
>To: Mark; Antenna Mailing List :>
>Subject: Re: [Antennas] Eighty Meter mobile or portable
>
>Hello,
>
>I hope this simple question doesn't start another war.
>
>What is the difference between 75 and 80 meters on the ham bands. Is there a
>difference? They are frequently interchanged. Are the ham bands broke up
>into two segments?
>
>Best,
>Wayne