Having two allowed me to venture into converting one to 160 meters with great success. I have wound a new tank coil on 3/4"PVC pipe with the ability to operate 160 80 and 40 meters.
Taps are at 6uH, 12uH and 24 uH for 160-80-40 meters. The 160 -80 meter operation will be controlled by a russian vacuum SPDT relay to shunt the 160 meter portion of the coil. When the 160 coil segment is in use the relay is opened and switches in an additional 130 pF cap on the tuning cap. L4 needs an additional 100 pF for resonance, and that will have an additional relay to switch it in and out.
Since I have the 24 VDC available, I will be adding an internal relay to switch the keying line, as the 85+ volts on the key line / mic PTT line to reduce shock and mic switch degredation.
The audio section is really stunning and reports on the audio have been well received.
Enjoy, Woody N4MQ