Rather than produce a transmitter to match the 2B, Drake designed a new line of equipment beginning with an SSB transceiver, the TR-3, in 1963. Again emphasizing size efficiency, the TR-3 was designed as a complete SSB station in a small package. Other design innovations included crystal bandwidth filters and a permeability tuned oscillator (PTO) capable of extremely linear, stable tuning and a dial resolution of better than 1 kHz across all amateur HF (shortwave) bands. Its size was so small, in part, because the power supply was in a separate chassis, connected to the transceiver with a multi-conductor cable. The AC-3 power supply could be installed inside a matching speaker cabinet, later designated the MS-4. An optional remote VFO (PTO), the RV-3 could be added to the system to enable split frequency operation (i.e., transmitting on a frequency different from the receiving frequency). The RV-3 (and, later, the RV-4) also contained a speaker.