Ham Radio Laser Communications

Laser communications can hardly be called the last frontier for Amateur Radio communications. There are any number of stations using this mode of communications operating with very simple and inexpensive homebrew equipment. Getting started in laser communications is easy. The information below will get you operational on laser with little effort or cost. The point values of having laser communications in a VHF and above contest is staggering. Given the grid square multiplier and the number of QSO points, laser can have a very significant affect on your score. Of course you need to have at least two people to work each other so build a pair of these. A laser equipped rover in a real asset in a contest.

Here is a parts list for building a single laser transceiver. Multiply the quantity on the list by the number of transceivers you are going to build. These make a great club project and are fun to build. That is actually what this was for the Mt. Airy VHF Radio Club of Philadelphia, PA.

QTY	ITEM	QTY	ITEM
1	Small box for electronics	1	1.5" of 1" aluminum angle for azimuth
1	1" X 2" vector board	2	long 4-40 screws for az-el adjust
2	4.7K 1/4 watt	3	pan head wood screws
1	47 ohm 1/4 watt	1	sheet metal screw
1	.1 mfd mini axial cap	1	ground lug - solder type
1	1/8" audio plug	1	8 pin IC socket
1	RCA plug	1	555 timer
1	RCA jack	1	pushbutton switch
1	9V battery clip	1	solar cell
2	9V batteries	2	4" foam backing board
1	Radio Shack audio amp #277-1008C	1	Velcro fastener - self stick
1	Laser penlight	1	double sided foam tape for battery
1	4" PVC pipe 12" long	1	heat-shrink tubing or plastic tape
1	4" PVC pipe cap	1	LED
1	18" of 1" aluminum angle rail	1	330 ohm 1/4 watt

The following is my construction project built using the Pack Rat design though I made some changes to the hardware and learned a few things along the way. I'll share those with you as we go along.

At the bottom of the page are some links to schematics and other information.

This first picture is how I mounted the solar cell on the foam board. The foam itself was cut out to be a reasonably tight fit inside the 4" pipe cap so that I did not have to glue it inside the cap. It is held in by a snug fit in the cap and then the cap is placed over the 4" pipe so as to very tightly hold it in place. Notice that I punched four holes into the foam, bent the leads from the solar cell over, and pushed the through the holes. This makes a nice neat assembly.

This next picture shows the finished assembly inside the pipe cap. I drilled a hole in the center of the pipe cap, tied a knot in the wires to act as a strain relief on the connections to the solar cell and then brought the wires out the rear of the cap. The strain relief knot is shown two pictures down. The knot is much larger then the hole which is just large enough to pass the two conductor wire.

The picture below is the finished tube. I cut it 12" long so as to have a nice tube length to work with for mounting purposes. Let me caution you about the 4" pipe. There is 4" PVC pipe, there is also 4" PVC pipe and then there is 4" PVC pipe. Make sure you get the right pipe caps for your 4" pipe or it will not fit. Each of the three sizes of 4" pipe that I know of must be made with a different ruler. They are close, but not the same. What I used is sold at Home Depot and is the least expensive of the three. It is known as Per Form as I recall. A 10 foot length was less then $4.00. That is less then half of the price of schedule 40 PVC pipe. And to make things even better, this pipe is black inside which might be helpful in bright light by reducing glare and reflections inside the pipe from ambient light. The other types of 4" pipe are both white inside. This stuff is not as strong but for a 12" piece, and what we are doing with it, it makes no difference what-so-ever, other then in the pocket book.

This next picture is the finished pipe assembly looking down inside of it. You can see that the edges of the foam backing board are completely locked in by the pipe in the pipe cap so it can not move. If you take a quick look at the previous picture you will notice that I did run a small bead of silicon sealant around the tube and pipe cap to hold them together. However, on the next unit I built I found that the silicon was not really important. The pipe and the cap form a pretty sturdy connection.

This picture is the Radio Shack plastic hobby box that the transmit electronics are built into. You can see the vector board standing on its edge with the battery leads and the CW key leads going to the left. The red and black leads on the right go to the laser and provide power to it when the CW key switch is depressed. I chose to use the aluminium cover that came with the box since it is stronger and the CW key switch is mounted in the lid. I'd suggest not using the plastic lid since it can crack pretty easily. In addition, make sure you carefully trim the vector board to fit snugly inside the box but not so big that it puts pressure on the box that will over time crack the box.

This next picture is the finished control box with the CW key switch mounted. The picture below that is the laser I used mounted on a small table top camera type tripod. These lasers are made for construction use and come with a diffuser lens that can spread the laser beam out across a wall and form a nice straight level line. It is magnetic and must be removed for communications purposes. You don't want to put out a laser line but instead a laser dot.

STAND BY THESE TWO PICTURES ARE COMING SOON

Below is the project built by the Pack Rats and the unit itself was built by Rick, K1DS.

Also needed are be some 2 conductor hook-up wire, and a couple rubber bands can be used to hold everything together.

You will want to build this on a wooden base which will also require some wood screws.

Here are couple pictures of the laser system but by Rick, K1DS of the Mt. Airy VHF Radio Club, better known as the Pack Rats. The top pictures are the transmitter end and the third picture is the receiver. As you can see, these units can be made very simply and easily. You could also do a lot more work and spend a lot more money, but not make the units work any better. The choice is yours to make.

Notice the Radio Shack audio amplifier on the back of the receiver. The speaker is built into the RS amplifier and emits a tone of about 800 hertz. This is a nice tone frequency for CW work. The push button switch on the top of the plastic box is used as the key for low speed CW. You could also use an actual hand key in its place; either through a jack and plug or hard wiring the key to the board inside the box. A plug and jack would be nice but this adds to the cost and complexity of the unit a small amount. Just let your imagination lead the way.

The transmitter and receiver schematics can be found HERE.

An edited version of the written construction instructions can be found HERE:

A PDF of the original instructions published in the Pack Rats newsletter can be downloaded HERE:

Here is a sample video clip of a laser system in use: 800K

Here is another sample video clip of a laser system in use: 800K