The FTDX101D is built to link the Amateur operating frequencies to a resistive impedance antenna of 50 Ohm. Find a appropriate antenna (dipole antenna, YAGI antenna, cubical quad antenna, etc.) fit for the specified service and bands. Construct the antenna and coaxial cable, or use an appropriate antenna tuner to maintain the impedance presented to the antenna connector FTDX101D for an SWR of 1.5 or less. Careful an-tenna and/or tuner planning will require optimal output, and protect the transceiver from injury. There might be large RF transmitter voltages on the antenna; mount it so it won’t be readily disturbed while it is in service.
I referred to to your question what ssb filter is for sub side of ft-101d. I found out in their user manual, there are several filter you can use.
In their user manual it is said to use a roofing filter.
Upon switching to the 9MHz IF, roofing filters attenuate powerful signals outside of the de-sired passBand. The roofing filter will attenuate components with undesirable frequencies. Tap [R.FIL] on the TFT panel to pick the SSB filter 3kHz, the CW filter 1.2kHz or the CW filter 600Hz. This also comes with an available 300Hz sensor.
Also it is possble to use SSB Narrow filter. But you will have to contact YAESU for the configurations.
Thank you for reading my article on what ssb filter is for sub side of ft-101d.