Wow the title say it all. No I am not going to rant about me being instructed to switch off my then beacon on 80 meters. At the end of the article I will come back to the title of this article. I will also give reasons why I constructed this beacon on 80m. (At the time there was already a beacon on 40m.)
Here follows the history of the "unlawful" radio beacon on 80 Meters.
The ZS1I 80 Meter Beacon was
operational from 22 August 2007 - 1 September 2008.
PARTICULARS:
Frequency:
3580 Mhz LSB
Mode: CW
Power: 350mW
Antenna: 40/80
Meter Rally Trap
Grid: KF15BT
Message: DE ZS1I BEACON
KF15BT
Keyer: ZS1I BEACON KEYER (New project using a
PIC12F675)
Location: Mossel Bay, South
Africa.
INTRODUCTION:
I never had
any intention to construct or operate an 80 Meter Beacon.
This
project started in April 2007 by co-incidence when I read an article
about a QRP Transmitter and PIC Keyer, which are successfully used to
operate a beacon. The construction of the transmitter was however not
the challenge as various QRP transmitter projects can be found in
abundance on the Internet. I was curious to find out how to key the
transmitter with a PIC. Various searches on the net revealed PIC16F84
Keyers with hex code and in some instances the source code for the
project. This was not what I was looking for. I wanted a PIC Keyer
that uses a minimal component count. As I had some PIC12F675's spare
the choice fell on this PIC. Very little information could be found
and I decided to write my own program with the available information
that I had on hand. This was a real challenge as my knowledge op
writing a source file is very limited. However I learned quite a bit
about this particular PIC when I played around with the UHF TRACKING
TRANSMITTER.
CONSTRUCTION DETAILS:
I
intend not to go into to much detail, as this will make the article
to long. MPLAB was used to compile the source, hex and project files.
I ran into several problems with many errors that had to be cleared
before I got a 100% success rate in compiling the hex file. This was
no guarantee that the keyer would key the transmitter, as I would
find out once I got everything rigged up. With the programming done
it was now off to the breadboard to setup the PIC and to listen if
the “message” is correct. I rigged the board and was ready
to test the “ZS1I BEACON KEYER”. Switching on I discovered that
the audio was “wiggly” and that the PIC did not repeat the
message. The CW speed was also too slow. Back to the start again and
after a day or two I was again ready for a second test. Remember I
did not use an inline programmer and had to start from the beginning
again. Well “ NO PAIN NO GAIN”. The second trial resulted in the
correct speed and audio, but no looping of the message, although I
did include the loop message in the program. Patience…. Patience
and Patience! Back to the start again. But how do I find the problem?
Getting up one morning around 04.00, I found the problem in that I
specified a wrong command in the loop function. Testing the PIC
showed that all seem 100% but I forgot about “Murphy”.
With
the PIC running “100%” it was time to build the transmitter. I
looked at a few QRP designs and finally decided on a transmitter,
which was developed by Wes Hayward – W7ZOI. It is called: “THE
LITTLE JOE”. With the help of John ZS6HK and Hannes ZS6LW, I
obtained the article and diagrams for “The Little Joe”. Making
the PCB and digging out the components from my junk box, I was able
to put the transmitter together within a week.
TESTING AND FAILURES:
Test
revealed that the transmitter worked flawlessly and that it was
“narrow minded”, just what I was looking for. The transmitter delivered a full 500mW of RF
Power to the antenna while keying the TX with a straight key. I
needed a small power supply to power the now ZS1I PIC KEYER. I
constructed the power supply unit and was now ready to rig the three
units together to hopefully have an 80 Meter Beacon. This is now were
“Murphy” showed up to confront me with all sorts of small but
irritating problems. With every unit rigged up on a temporary board
it was time to do the real test. The switch was thrown, the keyer
respond but no audio or RF out.
Great disappointment, but the challenge remains. Back to the basics. A LED with a resistor in series showed that the PIC and power supply are working. Just to make sure I used a piezo buzzer at the output pin to listen to the audio. This test was also successful.
Was the problem with the
transmitter? I was not sure about this theory at all as the
transmitter was working 100% when using the straight key. Just to
make sure I connected the key and receiver up again with the very
same result that the transmitter is working 100%. Remember I had no
guarantee or information that this setup would work with the keyer
that I built let alone the constructing of a beacon from these units.
I tried several ideas to get all the units to talk to each other. The
end result was that two PIC12F675’s were send to the dustbin. A PCB
track turned to a small ball of copper and the well-known smell
occupied the workbench. The call it the magic smoke. Give up……No …. No!! This is not about
giving up but rather about finding a solution and get the thing to
work. Difficult if you live in an area where you are currently the
only radio amateur experimenting with PIC’s and QRP
transmitters.
Back to the early morning faultfinding
session at 04.00. Do you also find those days when everything just
seem to go wrong, no matter what you try. Don’t worry you are
definitely not alone. Stupidity is not limited to just certain people
in life. When I tested the beacon on the breadboard, I used an
admission transistor to do the switching although the transmitter had
its own switching transistor. After the tests I decided not to use
the additional transistor at the output of the PIC. My stupid reason
being that the transistor on the TX will be used to do just that.
Well I found out the hard way that this is not how it is suppose to work. The early morning coffee session brought some clarity to my “hard drive”. After installing the transistor and limiting resistor it was back to the smoke-test. Low and behold the beacon was now fully functional. What caused the two PIC’s to go up in smoke? My humble opinion resulted in the following theory. The TX uses positive keying with 12 volt coming through on the line towards the PIC. So every time that you key the PIC 12 volt is going into the output of the PIC and that causes all the nasty smoke to come out of the PIC and the PCB track of the transmitter. Wow some have to learn the hard way in life, but what is life without a smoke or two?
FINALLY:
The
end result was the sweet music of morse code coming from a project
that emanated from a thought and the shear curiosity to construct
something that might be useful.
Even if I had to take the beacon off the air, I achieved and learned something worthwhile that nobody can ever take away from me. I would like to share this article and info with fellow homebrewers to encourage them to keep those soldering irons smoking.
Never ever give up on any project.
Even if it goes up in smoke several times. Build on your dreams
even if this means that you must get up at 04.00 in the morning. Ensure that you are on the right side of the law and that you adhere to the Amateur Radio Code!
Isn’t this what amateur radio is all
about?
Experimenting and Developing our skills as Radio
Amateurs!!
PS. I experimented in using different antennas for the beacon. I still have my notes on this hopefully somewhere amongst my amateur radio records. I will not go into detail here about all the experiments I conducted around the beacon as space will not allow it. This was a great experimental project that lasted for more than a year before I took the beacon willingly off the air without further instruction to do so. I thank all those radio amateurs that assisted me in providing with reception- or other reports.
Now was this beacon unlawful on 80 Meters. At the time I could not find any regulation or directive that beacons are not allowed on the 80 Meter band. I challenged the then councillor to go ahead with his threats. Nothing happened and I concluded my experiments without further "bullying". Thankfully the then councillor is for many years no longer a member of the SARL Council.
I would advise radio amateurs today not to operate a Radio Beacon on 80 Meters. I know that there is now a directive that beacons is not allowed on 80 Meters. Contact the relevant SARL Councillor (thankfully not the one that threatened me) for more information in this regard and before operating any radio beacon on the spectrum.
No why this article? It should be clear that this article is about experimenting one of the corner stones of amateur radio. This is not about bashing or digging up old cows out of the grave. (no such expression well there is one now.) This article was posted with the sole intention to encourage radio amateurs to experiment more with various aspects of amateur radio. I experienced many hurtles and even threats that I had to overcome. I did overcome them all. You can also do it.
No I have no electronic background of any kind only a legal background and that does not help me in any way. All it takes is the will to learn, read and build. Come on take up that soldering iron and learn from your mistakes but the most important aspect is to share your findings with other radio amateurs as I am now doing. Hopefully this will encourage others in this regard.
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