This is another Yaesu FL-2100Z that I converted to Russian GI-7B triodes. This is a straight forward conversion... Remove the old tubes and tube sockets (horizontally mounted), remove the bottom mounted fans, install new sockets in place of the fans, power supply mods, install a bias control circuit, installed two fans to cool the filament connections, two additional fans to cool the anode connections, mods to the tuned input, relocated the output padding caps, installation of a high voltage interrupter, etc. That's all :-) Here's a few pics and info...
This is a version of the bias circuit I used in this conversion.
A fuse was installed in the cathode circuit.
Protection installed on both panel meters.
I wired it for 110v operation.
Tube socket used in the conversion...
Sockets spaced below the chassis...
Sockets spaced carefully, to allow anode clearance between the plate choke and chassis wall.
Relocated tank padding caps.
Plate bypass cap...
Testing the HV supply and interrupter...
Interrupter and glitch resistors installed...
Bias switching transistors...
Connections between filament choke and socket...
Fans to cool base of tube sockets...
Voltage doubler for DC control circuit...
HV interrupter (L), glitch resistors (R)...
30w drive used to test tuned input and for initial tuning...
Bias transistor...
Tuned input with capacitor changes in place...
Mod to tank circuit on 10 meters...
HV transistor for bias control.
