[ARC5] Dummy load for BC-230?

[David Stinson]

Morning, Ian.
The original dummy-load for the set was 5 ohms in series
with 100 pFd. I have one here but don't use it.

The Graybar BC-AL-230 on my bench now has 
6AQ5 in all stages. The bias resistance (the 20K on
the end of the mounting board nearest the coil pack)
has been reduced to about 12K. 
I have a 100 pFd "doorknob" cap in series with 
the antenna output.  That goes to a wattmeter 
and a 50-ohm dummy load.
A+ is 13.2 V and B+ key-down is 315 V 
from the dynamotor.

The coil pack is a Graybar C-272, 3.2-4.0 MC
3800 KC appears at 1985 on the freq. dial.
Then tap on the antenna/PA coil is between turns
14 and 15, counting up from the bottom (connector)
end of the coil. Output tunes to resonance at 
about 2/3 mesh on the cap. 

I'm getting 4.5 W out into the load.
Just to isolate any troubles-
if you have tubes in the Modulator stage,
disconnect their plates so they don't draw 
current and load-down your B+.
There could be other gremlins in there.

That bias change is not "the last word" and
I will probably tweak on it a little more 
before calling it "good."   12K may be too low.

73 DE Dave AB5S


----- Original Message ----- 
From: "Ian Wilson" <ianmwilson73 at gmail.com>
Subject: Dummy load for BC-230?


>I have jury-rigged a couple of 6AQ5 to fit the osc and RF amp
> stages in my BC-230-AS. It appears to be doing the right
> things, up to the RF output.