Back in June 1984 Radcom featured the fist part of several by the late Lorin Knight, MIEE (G2DXK), entitled 'A Transceiver for the HF Bands'. The first part covered the crystal ladder filiter in some detail. The bandwidth was switchabe by reed relays from 2.4kHz to 300Hz (for CW).
The first part is here, and might be of interest, as might other parts of the project in subsequent Radcom issues:
https://www.americanradiohistory.com...om-1984-06.pdf
He also designed a valve linear amplifier. using a pair of 6146Bs. I greatly enjoyed reading both articles and at the time, was still interested in amateur radio so came close to building them, but later embarked on the well known G3TSO rig, which used the Plessey series of communications ICs - long since obsolete.