In a typical single-sideband transmitter, at what frequency is the sideband filter tuned?

In a classic filter-method single-sideband (SSB) transmitter, the initial SSB signal is generated at a fixed intermediate frequency (IF) before being mixed up to the final operating frequency. The balanced modulator uses a fixed RF oscillator to create the initial double-sideband signal. Because this initial generation happens at this specific fixed frequency, the sideband filter must be tuned near this fixed RF oscillator frequency to properly select the upper or lower sideband. It strips away the unwanted sideband right after the balanced modulator. The filter is not tuned to the final operating frequency or the VFO frequency. Those frequencies come into play later in the circuit, when the mixer transposes the already-filtered SSB signal to the desired transmit band.