thinking:
1:1 input transformer -> source follower mosfet -> 1:10 step-up -> 6 to 8 parallel EL84's SE UL.
Running 300v 39mA a piece. maybe a 600:8 output tranny.
fixed bias on output stage to secondary of 1:10.
very simple... no coupling caps.. all major voltage gain by 1:10 and output stage.
power supply: cap multiplier circuit. suggestions?
DC on EL84 filament supply.
comments? suggestions?
will this work and what should I look out for?
thanks!
1:1 input transformer -> source follower mosfet -> 1:10 step-up -> 6 to 8 parallel EL84's SE UL.
Running 300v 39mA a piece. maybe a 600:8 output tranny.
fixed bias on output stage to secondary of 1:10.
very simple... no coupling caps.. all major voltage gain by 1:10 and output stage.
power supply: cap multiplier circuit. suggestions?
DC on EL84 filament supply.
comments? suggestions?
will this work and what should I look out for?
thanks!
If it were me the first consideration is confirming a 1:10 doesn't balk at driving the grid capacitances of 8 parralled el84s. Have you considered a source follower, maybe DC coupled, to the el84 grids and using the 1:10 as the input stage? Drops one tranny, replaces it with a smaller signal, higher quality unit and the follower will better drive the output. Since you're going fixed bias you already have a negative supply handy.
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