> The original capacitors are just fine if you have a tube
> load
> impedance of 400-600 ohms. The added coil creates an
> L-network which
> transforms the approx 4000 ohms of the 3-500Z down to that
> value.
>
> As I mentioned, this technique is covered in any recent
> ARRL handbook
> in the HF amplifiers chapter. The example they give is for
> ten meters,
> but the principle applies equally to six or any band for
> that matter.
The only problem doing that is stability.
It generally works OK to do that with a very stable tube
like a 3CX1500A7 or 3CX800A7, but tubes with long grid leads
can get a bit squirrelly.
73 Tom
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