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This is a fun and very learned group..I learn more every day I am here.
On Thu, Mar 14, 2019 at 9:17 AM Dave Benson <davek1swl@...
re class-C vs class E
There's another straightforward way to tell...by looking at the schematic.
The components on a class-E amplifier's collector/drain circuit should be resonant at the operating frequency. This primarily includes the collector/drain's RF choke and a capacitor to ground. (The PA device's output capacitance also needs to be factored in. )
If there's a capacitor to ground on the PA drain/collector, chances are good it's designed for class-E.
On Thu, Mar 14, 2019 at 6:18 AM David Wilcox via Groups.Io <Djwilcox01email@example.com
OT I know.
Still looking for a Palm Pico Paddle. Thought one of the listeners here might have one to sell.
Dave K8WPE. Djwilcox01 at gmail dot com
David J. Wilcox K8WPE’s iPad
On Mar 13, 2019, at 11:02 PM, Charles W. Powell via Groups.Io <doctorcwp@...
Oh good. Some more fun with the scope!
Chas - NK8O
On Mar 13, 2019, at 8:30 PM, WA0ITP <wa0itp@...
Correct! Put your scope probe on the collector
of the finals If it is in Class E, You should see only positive
rectangular pulses, such as the ones below. The LPF filters out
the harmonics making it sign wave.
Dave has mentioned that the HT runs in Class C. The second graph
below show most classes and their conduction angles. Class C is
sinusoidal but is biased off for most of the cycle. It can be
very efficient too.
I love this radio stuff.
On 3/13/2019 6:32 PM, Charles W. Powell
via Groups.Io wrote:
Question: Can one tell from the waveform of the output of the
BS170s what class amplifier is in operation? If I understand
correctly, Class E would show only a series of pulses, whereas
class C would show a “round topped” upright square wave.
Any guru comments on this?
Chas - NK8O
Good question! (and nice going on all the
There shouldn't be much difference in
power output between the two bands. There's plenty of
drive from the paralleled logic gates. As a result,
the PA devices should be in saturation either way. As
an aside, I'd heard from someone who tried the scheme
on 50 MHz. He got 4W out.
From what I've heard, the QCX may be more
prone to low power output. I don't know if that's a
common occurence, though. The QCX is configured for
class-E but the component values don't make sense to
me. In the case of the Hilltopper, I was concerned
about peak voltages (4*Vcc) and tolerance stack-ups.
As a result, the Hilltopper runs class-C and not
73- Dave, K1SWL
On Thu, Mar 7, 2019 at
8:45 PM StanWB2LQF <sjl219@...
to purchase a Hilltopper 40 but first I would like
to know how close to 5 watts output I can get from
12 VDC? I built five QCX transceivers and not one
of them ever approached 5 watts on 12 VDC and they
also use three BS170 transistors.
fairness to QCX Labs, they do indeed specify that
the QCX transceivers operate on approx 6 to 16
volts and, of course, output varies directly with
question: For whatever power out 12 VDC provides
for the Hilltopper 40 should I assume it will be
EQUAL or LOWER for the Hilltopper 20?
advance for some enlightenment; I'm a new group
73 de KB9BVN