[ARC5] BC-AS-230 Transmitter Follies, Part 1

[Tim]

In a pinch, how about a Mk-1 Mod-0 incandescent light bulb....appropriate
wattage....with a series variable capacitor.

Tim
N6CC

On Wed, Dec 31, 2014 at 11:40 AM, Dennis Monticelli <
dennis.monticelli at gmail.com> wrote:

> Ben,
>
> Glad to hear that the rig seems to be working.
>
> I would like to comment on that 5 ohm wire-wound resistor.  I would be
> suspicious of it because the effective series inductance (ESL) would likely
> be a significant percentage of the 5 ohm stamped resistor value.  For
> example, it only takes 0.11 uH to equal 5 ohms of inductive reactance at
> 7MHz.  It's the low value wire-wound resistors that you have to watch out
> for.
>
> Dennis AE6C
>
> On Wed, Dec 31, 2014 at 10:49 AM, Ben Hall <kd5byb at gmail.com> wrote:
>
> > Good afternoon all,
> >
> > This will be quick - a certain 9-year old boy is wanting to go out into
> > the garage to fiddle and tinker with stuff.  ;)
> >
> > Check-out of the BC-230 went swimmingly.  I didn't find any obviously bad
> > capacitors, bad resistors, or any hacked wiring.
> >
> > Last week, I built up a phantom-antenna / dummy load consisting of a
> 5-ohm
> > wire-wound resistor in series with a 100pF door-knob cap.  At some point
> I
> > will replace the wire-wound resistor with something non-inductive, but I
> > figured for my testing, this was 'close-nuff.
> >
> > This morning, I installed four of my tube adapters with 6AQ5's installed
> > and built up a temporary harness that would allow the set to transmit in
> CW
> > mode.
> >
> > After a break for lunch, I turned on the +12VDC supply, let the heaters
> > warm up, turned on my variable B+ supply, let it heat up, and slowly
> ramped
> > the voltage up.  I was delighted to see RF output on the scope, antenna
> > current indicated on the meter, a frequency output in the 5 MHz region
> > (which is appropriate for the coil set installed) on the counter, and a
> > nice-looking sine wave on the scope.  :)
> >
> > I max'ed the antenna coupling control and got the nerve to up the B+ to
> > 250 VDC.  At 250 VDC, the antenna current meter was reading 0.6 amps of
> RF
> > and 400 Vp-p on the scope with a nice looking sine wave.  (note that I'm
> > not real trusting of that 400 Vp-p measurement - seems wacky to me)
> >
> > At some point I'll get up to the 300 to 350 VDC suggested in the manual.
> > But for now, I'm happy to know it is working as-is w/o any repairs or
> > tweaking needed.
> >
> > thanks much and 73,
> > ben, kd5byb
> > ______________________________________________________________
> > ARC5 mailing list
> > Home: http://mailman.qth.net/mailman/listinfo/arc5
> > Help: http://mailman.qth.net/mmfaq.htm
> > Post: mailto:ARC5 at mailman.qth.net
> >
> > This list hosted by: http://www.qsl.net
> > Please help support this email list: http://www.qsl.net/donate.html
> >
> ______________________________________________________________
> ARC5 mailing list
> Home: http://mailman.qth.net/mailman/listinfo/arc5
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:ARC5 at mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>