[ARC5] BC-230 mic

[AKLDGUY .]

Hi Ben

> The conventional "wisdom" is that these laptop power supplies, being of a
switching design,
> create a lot of hash and RF noise.

Yes, I thought of that too, but am still keen to try one with the braid of
its cable directly bonded
to the chassis of the power unit which will not only be electrically
connected to the chassis of
the receiver, but will connect to it much more directly since the entire
setup will mount on a
rack constructed of aluminium angle. There is no such close bond in normal
operation and any
hash can find its way from appliances to the receiver via power
distribution wiring.

Also, we have become fixated with 50 ohm unbalanced transmission line to
the antenna. It's my
theory that the braid of the coax picks up radiated hash from appliances,
so that hash voltage
exists between the braid and the inner conductor. Balanced feed should
eliminate most of that.

My plan is to link couple the transmitter & receiver to a coil with a split
stator capacitor that can
be peaked up on band noise while receiving. Balanced feed taps will be
positioned on the coil
for best match. Once found, the position should hardly ever need changing
since operation will
be on the AM net frequency. Cruising up and down the band with the BC-230
would be a pain.

The antenna here will by necessity be a very short dipole, 5 feet off the
ground. I'll be happy
with NVIS propagation to talk to the locals.

73 de Neil ZL1ANM