[ARC5] BC-230 progress in ZL

[AKLDGUY .]

Progress on building a power supply for my BC-230 has been slow, due
to summer heat exhaustion.

The weather since January 1st has been warm & sunny with clear skies
day after day, except for 2 days when there was briefly some drizzle.
All my drilling and soldering is done outside on a concrete landing and
the temp out there under the balcony can approach 30C or 86F.

Here are a couple of photos of progress so far.

https://www.flickr.com/photos/60939566@N02/16333840306/in/photostream/
https://www.flickr.com/photos/60939566@N02/16358066511/in/photostream/

Maybe they'll give someone some ideas.

The two chassis are mounted on a 440mm (wide) x 330mm x 3mm sheet
of aluminium that will form the lower shelf of two; the upper shelf will be
the
same size and will support the BC-230 and a receiver that I will eventually
mate with it (I'm thinking Bendix RA-1B, drool).

These shelves will mount on a rack made of 40 x 40 x 3mm, or similar.

The 325V power supply (right unit) plugs into a 230-230 VAC isolating
transformer rated at 1KW, which isolates the lethal mains voltage.
The resulting balanced 230 VAC is bridge rectified to give about 325 VDC.

The other unit consists of termination points (tag strips) for the PL-64
cable
which will be secured to chassis by the copper saddle clamps. This cable
will go into the little black box and thus the wires will pass thru the
chassis.
The large heat sink is for the series pass transistor of a regulated 12.6
VDC
supply for the heaters and mic preamp (the latter will be mounted in this
unit).
The heat sink is stood off from the chassis by four 15mm nylon spacers, so
the transistor can be bolted to it with no need for a mica insulator.

This heater supply will initially run from a 19.5 VDC switcher power supply
from a junked laptop, but if it proves to be too noisy, I'll mount an 18 VAC
transformer on the right chassis with a bridge rectifier and capacitor.

The microphone has been pulled from a junked taxi radio and is believed
to be of electret type. I believe that with adequate decoupling, the 14V
feed
from the BC-230 mic transformer can power the preamp and the mic itself,
with the preamp's audio being developed across the decoupling resistor.
In other words, single-wire feed for both audio and power. If the mic cannot
be adequately decoupled, I'll power it from a 'dead' 9V dry cell battery.

I've made no provision for CW, although a switch could be mounted on the
front panel next to the mic cable, and I might add this function later.

There's enough room on the left chassis to mount a meter, which can have
a flying lead that plugs into the meter jacks on the BC-230.

73 de Neil ZL1ANM