[Boatanchors] Link coupled output?

[shoppa_boatanchors at trailing-edge.com]

> I am trying to determine what characteristic impedance transmission
> line to use with my homebrew 1948 transmitter.

I didn't see you specify the must crucial parameter: what band(s)
you're going to cover.

If the antenna side of the link is not resonated with a tuning capacitor,
then the inductance of the link coil has to be high enough that the
impedance of the link at operating frequency is small compared to the
transmission line.  At 40M or 80M the coils become unreasonably large
even for low-impedance (50 ohm) feedlines, and I'm not going to say it's
impossible to do this with 300 ohm line but it's even harder there.

The 50's/60's era handbooks are very clear on this subject.  There's
a couple pages under the heading "INDUCTIVE-LINK COUPLING" in the
HF transmitter chapter.

With tuned output links things are not so hairy.

But if I were you I'd build the transmitter to fit the antenna/feedline
even if this means going to pi-output...

Tim.