It's pretty simple really. This style of frequency assignment is typical of
MIL channel assignments, MARS specifically. For MARS at least, the normal
operating standard is to set the dial frequency 1.5Khz BELOW the assigned
channel frequency (for USB channels assigned as the center of a range like the
60M channels are).
Let's say you have a 2800 Hz transmit bandwidth, F is the assigned channel
frequency, and the carrier setpoint against the transmit filter is such that
your transmit frequency range (audio range) is 100Hz to 2900Hz. For USB, if
you put your "dial" frequency on the channel, your transmit frequency range
would be F+100Hz to F+2900 Hz. You need to get that high limit down to
F+1400Hz -- so you would tune down to put your "dial" on F-1500Hz -- which just
squeezes your transmit bandwidth into the range.
Technically the right "dial" setting depends on transmit bandwidth and carrier
setpoint, which I suspect is different for every radio out there.
Practically speaking, a "dial" setting of 1500Hz BELOW the assigned channel
frequency probably works as a reasonable compromise. And of course transmit
bandwidth has be 2800 Hz or less. We do need to adopt a standard so everyone is
actually on the same frequency.
Grant/NQ5T
> Hmmm.... Come on guys, stop squabbling and prove you actually did pass a
> technical exam to get your license... If the quote below from Dave's message
> is
> correct, the regulation is already flawed and every person using one of the
> assigned frequencies will be a pirate... (jeez, am I the only one awake on
> here?)
>
> QUOTE:
> on
> the channels 5332 kHz, 5348 kHz, 5368 kHz, 5373 kHz, and 5405 kHz. Amateur
> operators shall ensure
> that their transmission occupies only the 2.8 kHz centered around each of
> these frequencies.
> UNQUOTE
>
> So now me hearties, shiver me timbers and explain to me parrot how the upper
> sideband of a suppressed carrier on 5405, for example, will occupy 2.8 kc,
> centered around 5405? i.e. between 5403.6 and 5406.4?
>
> Denny <snicker>
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