re: the current 4cx350 project thread.
>
I've done this amplifier project once already. I've actually gone
back to look through my notes and final as-built design. There
were some issues about the 4:1 toroid. Although the numbers
worked out on paper, I had a hard time getting things to work
with the actual circuit.
Maybe it was the ideal part values vs what ends up in the mix.
What I ended up with was the 9:1 toroid and termination
resistor circuit. That allowed me to provide ample drive with the
Icom 511 (which is going up for sale soon) 10 watt output.
>
I would have preferred to use the 4:1 toroid, but I could never
get the circuit to preform as well I expected and calculated for
the 52MHz band. Going to 9:1 was just easier and has proven
to be stable.
>
hope that helps
cheers
skipp
>
>If I have 10W and I want 60V and half the power
>is going into my tubes and half into my resistor it looks
>like a 1:6 turns ratio and an 1800ohm resistor will get me
>the right swing from my 10W and look like 50ohm to the
>exciter.
>
>So, why do I need tuned input?
>
You need 60v pk to drive the grids. 10w-rms / 50-ohms is 32v pk. A
bifilar toroidial transformer would increase the potential to about 60v
peak. The terminating R would be 200 ohms.
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