Some History:
At one time all receivers had variable BFO's, they were tunable about 3 kc.
above or below the IF frequency. The operator could set the BFO to fit
filters, QRM, personal preferences, etc. For a number of reasons, the
variable BFO was replaced by a crystal controlled oscillator. By convention
the "USB" crystal was used for CW reception. To accommodate various filter
widths, many designers used the "USB" oscillator and moved the passband of
the filter to a frequency that allowed for proper placement of the BFO
signal on the slope of the filter.
I believe that the Collins S-line was the last Amateur receiver to
incorporate a variable BFO.
Jim
> You always have a "sideband to worry about" when operating CW. Good rigs
> allow you to select either a LSB or USB passband. Older rigs didn't give
up
> that option so you were forced to live with the designers decision to
either
> use a USB or LSB passband when operating CW.
>
> While in the CW mode, slowly tune up the band. When you encounter a CW
> signal, if the pitch is high to start and then transitions to a lower
pitch
> as you tune up the band, your rig is using the USB passband. If the pitch
> starts low and moves high, your rig is using the LSB passband.
>
> ----- Original Message -----
> From: "rojomn" <rojomn@charter.net>
> To: "Michael Rudzki" <n8mr@hotmail.com>; <writelog@contesting.com>
> Sent: Saturday, February 08, 2003 04:39
> Subject: RE: [WriteLog] Bandmap and CW-USB in FT-920
>
>
> > Why not just command it to CW period. No sideband to worry about?
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