The
iDuino
kit is an $18 clone of the Arduino and came recommended as an
inexpensive
way to become familiar with microcomputers without having to climb a
steep learning curve. The iDuino is designed to be plugged into a small
solderless breadboard.
Once
the kit is completed, and the software loaded into your computer, you
are instructed to download a "sketch"tittled
"Blink" to your iDuino. If everything is working correctly the LED on
the iDuino will start to blink.
/* Blinking LED
*
* Turns on and off a light emitting Diode (LED) connected
to a digital
* pin, in intervals of 2 seconds. Ideally we can use pin 13
on the
* Arduino board because it has a resistor attached to it, needing
only
* an LED
*/
int ledPin = 13
//
LED connected to digital pin 13
void setup( )
{
pinMode(ledPin, OUTPUT);
// sets the digital pin as output
}
void loop( )
{
digitalWrite(ledPin, HIGH);
// sets the LED on
delay(1000);
// waits for a second
digitalWrite(ledPin, LOW);
// sets the LED off
delay(1000);
//waits for a second
}
It is evident from this very first sketch that the iDuino
could be used to key a QRSS transmitter, in fact all
of the information needed to do so is available here in
this
first sketch.
I assembled a "generic" MEPT and used the 5V available at
the output to key the voltage to the final amplifier via a relay. The
result was a QRSS3 mode where the dots are 3 seconds long and the dahs
9. I soon received a report of the MEPT's 50mw signal.
Mark, KU7Z, sent me this screen shot from his QTH in
Northern Utah and it exemplifies a QRSS3 signal.
Here is the sketch used to produce the QRSS3 signal.You can readily see how the iDuino allows you to produce just
about any message you might need.
Well, this worked out so well I decided to try something different. I
added an additional trimmer cap in series with a Red LED to the
oscillator circuit. Instead of keying the relay, the output voltage is
applied to the LED to produce an approximate 4 -5 Hz frequency shift.
The power to the amp stays on throughtout and thus produces a
continuous RF output. A sketch like the one for
QRSS3 can be used for
this mode also. The result is an 50mw FSKCW signal and a couple more
screen shots, this time from California, a little farther and a little
weaker.
This one from Stu,
N6TTO
And this one from
Mark, K6HX, much weaker.
So far, so good, how about DFCW or Dual Frequency CW? Here is a picture
of how it looked on Eldon's WA0UWH, Seattle Grabber on March 27.
The signal on the bottom
is from David, WA5DJJ. The one above that is Perry, KC7VHS, along with
the flying W of Bruce, WIBW. I had increased my power from 50mw up to
122mw. In DFCW mode the dits lie along the baseline and the dah shifted
up in frequency, in my case a little less than 2Hz. There is a break in
the RF signal between characters, and also between the elements of the
characters.
Two output pins are needed for this mode. We can use one output pin and
relay to key the voltage for the transistor amp like we did during
QRSS3 to control the RF output.
Five of the iDuino pins may be used for analog output and since we
don't want the full 5Hz shift for DFCW they provide a method to vary
our frequency shift by varying the voltage applied to our LED. Pin 6 is
one of the analog pins and the one used in the sketch. It is identified
as "int ledAPin = 6;" at the beginning of the sketch and pin 7
used to key the relay as "int ledBPin =7;".
In the sketch you will see "analogWrite(ledAPin, 108);" whenever a dah
and it's corresponding frequency shift is desired. This translates to a
voltage of 108/255 X 5V applied to the LED instead of the full 5V used
during FSKCW and results in a shift of about 1.8Hz that can
easily be adjusted.
After
operating DFCW for a while I decided to try alternating the FSKCW and
DFCW modes in an experiment to try to determine if either mode would
exhibit an advantage over the other. All that was required was a little
cut and paste, along with adding some additional space between the two
modes.
And the resulting screen shot from VK6DI's Grabber
located in Western Australia.
David, WA5DJJ's
strong signal is along the bottom of the screen, mine not so
strong but illustrates the alternating modes. Conditions on 30 have
been
good lately with propagation to Australia possible both evening and
morning. Look at VK2ZAY's neat signal!
Here are
a couple of screen shots provided by Colin, G6AVK. My
signal is the very weak one along the bottom and Colin makes the
comment that sending "dual modes make it a whole lot easier to read".
Well that is good enough reason to end my little experiment to
determine which
mode might be better and follow his advice and continue to send both.
My "generic" MEPT, consisting of a modified Crystal Oscillator and
Buffer Board from NightFire Electronics mounted inside a tin can with
single transistor amp mounted on the lid currently running 122mw.
