[ARC5] BC-AS-230 Transmitter

[AKLDGUY .]

> For 80-75 Meters, use a 100 pFd RF "doorknob" cap
> between the ANT post and a 50-ohm antenna.
> If running 40 meters, use 50 pFd.

Some of us have not enough space for a full size dipole, so
a 50 or 72 ohm match is impossible. In my case, there's only
about 6 meters from fence to fence so I'll be forced to set up
a very short dipole.

What I want to try is an (unbalanced) 2-wire feed from the
BC-230 to a link coil wound at the centre of a matching coil.
The bottom end of the link (connected to the G terminal of
the BC-230) will form a 'ground' terminal.

There will be a split stator capacitor across the coil with its
frame connected to the 'ground'. Taps on each side of the
coil's centre will go out via 300 ohm ribbon cable to the dipole.
The capacitor may need to be made up of 2 separate units
and a gearing arrangement, as split stator capacitors of the
expected size are not readily available.

This classic balanced matching system of the 1930s before
coax came into widespread use should work, but I'm not
expecting DX contacts. I'll be happy with local NVIS contacts.

I'm well on the way with conversion. A half dozen 6AQ5's have
arrived and I have cut out 4 circular pieces of Perspex (aka
Plexiglas), to which are bolted 1/8" and 4.0mm brass bolts that
simulate pins. The length of the bolts: 18mm, cut down from 25.
Diameter of the Perspex: 34mm. The Perspex pieces sit up off
the tube socket faces due to the brass nuts on the undersides.

The Perspex pieces are also fitted with 15mm nylon standoffs
(readily available) which come with 3mm threads. Each 6AQ5
tube socket will sit on its 2 spacers, held by 3mm zinc screws.

73 de Neil ZL1ANM