[ARC5] BC-230 Biasing and 40 Mtr CW

[David Stinson]

One thing I need to clear-up from my last posts on using
6AQ5 in the BC-230 by rebiasing:  The bias changes
only apply if you want to use the rig on AM.
If CW only is wanted, the original 20K resistor seems
to work OK with 6AQ5 and others.
I get 4 Watts out instead of 5 for CW but the tubes
aren't "pushed" as hard at the higher bias.
I just keep learning on these things.

Using the rig on 40 CW:
Seems no matter how one fiddles with the BC-230
in MOPA configuration on 40 meter CW, it's gonna chirp.
"Sing" might be a better word.  Some 100% reversable
changes will put the rig on Crystal control and give a nice,
clean note with about 3.5-4.0 W out.

Place the rig bottom-up with the tube sockets at the top
and the coil pack mount facing you.  The second tube
from the left is the OSC.  There is a dual oil-filled cap
with terminals just to the right of the socket.  The bottom
terminal has two wires- one goes to the coil mount, the
other brings B+ to the bypass cap.  Disconnect the wire
that goes to the coil mount.  Insert a known-good crystal
between the capacitor terminal and the coil mount lead.
Next, we shunt-feed B+ back to the OSC. by connecting
a 100-ohm 1-watt resistor in series with an RF Choke
between the capacitor terminal and the OSC plate connection.

If you are using a 6-7 MC coil set,
turn the FREQ dial to around 1700.
If a "repurposed" 5-6.1 coil, you may have to hunt around.
Power-up the rig and key-down while monitoring the xtal freq.
Crank on the FREQ control +/- a few hundred divisions.
If all is well, you'll find a point where the crystal breaks
into oscillation and takes-over from the "normal" MO
operation.  First tune for maximum output, then check
each side of the "peak" for best crystal operation and note.
On one side of the peak, the crystal will chirp
and fail to oscillate reliably.  On the other, you will trade-off
a small amount of power for reliablity and a clean note.
Peak-up the PA tuning and check neutralization.
My "peak" power with 6AQ5s and a 20K bias resistor
is just over 4 W out.  The "operate" point is about
3.5 W out and sounds excellent.
Output is dependent on crystal activity.

GL OM ES 73 DE Dave AB5S