This is a TenTec Century 21, model 570 (analog version). It was a junker, but I had other parts rigs/donors to help with restoration. This is from about 1975, and is a great CW rig. It has a direct conversion receiver, a 3 stage audio bandpass filter, does about 50 watts, has an internal ac power supply, rit, etc.
This one had blown finals, bad power supply, bad chip in the audio filter, the VFO was frozen, crystals missing, front panel push buttons were intermittant, was nasty, and the case sections were scraped up and peeling. I suspect it had been used for a parts rig and the bad stuff swapped back in.
The VFO is actually a PTO (permeability tuned oscillator). Essentially a coil where the slug in the center moves in and out via the front panel tuning knob. Many models of TenTec used this design. It works pretty good, but well known for locking up when the grease dries out with age. There are several pics showing the disassembly and repairs to this section.
I compounded the front panel and recovered the cases. You can see the recovering process, here: https://wb4iuy.blogspot.com/2021/02/re-covering-ten-tec-cabinet-sections.html
The first photo is with the problematic pushbuttons replaced with new stainless buttons that look nice :-) I ran it in Studio A a bit with the old buttons, and decided they had to go!
