Introduction: Poor Man's Radio Telescope
A way to peer into the radiosky using little more then junk found on the side of the road.
Remembering back to my 10th birthday. I recall receiving a book on outer space. I believe it was published by National Geographic. This was by far my most prized book in my somewhat limited collection of the time.
In it there was a rough outline of a radio telescope. This diagram so intrigued me that for years in the back of my mind I dreamed of being able to play with one.
Indeed years have past, careers, children, and everyday life was by far the most important of responsibilities. Then it happened. I spotted a 10 foot satellite dish in someone's trash.. I quickly made off with it and all its components.
The mount was in pretty bad shape. It appears to have some serious wind damage, and the pedals of the dish are in less then what I would consider acceptable shape.
None the less I slapped it all together. In the picture you can see my stinky trashcan mount. It was good for a quick test but boy did it stink.
Step 1: An Examination of the Feed Assembly
Here we see the feed horn and low noise amplifier. All the dish components were hauled to the curb except the actual receiver unit. The bolts holding the wave guide and the amp onto the feed horn had to be purchased. Getting this feed horn back into working order took a little bit of time. It seems that the feed horn assembly was home to a community of wasps. I never realized this before but wasps build there nests to last. It took a good bit of probing and a little 409 to clean it up nice.
This is basically the meat of the system. It takes the focused energy of the dish and downconverts it into a usable signal and then amplifys it.
How is all this powered you might ask? The voltage actually travels down the coax cable that is delivering the signal to the next stage.
The polorizing servo is basically left alone, but for those of you that are curious it's a little motor that turns the antenna inside the feedhorn for better reception.
Step 2: An Examination of the Electronics
Here we see the power supply and a satellite finder meter.
The power supply is home made, 15 volts regulated. I actually picked up the greater quantity of this at a junk store for 3 dollars.Its not as clean as I want it to be but I'm working on it.
The little fat coil hooked up on the right of the power supply is a choke I placed in the voltage path so the signals coming from teh dish do not seep back into the power supply.
The satellite finder meter I just received in the mail a few days ago. It receives from 950-2250Mhz. This is the second most important part of the arrangment. This takes the total power of all the signals that are coming from the dish and converts them into a meter reading. This is known as a Total Power Receiver .
I hooked all this equipment up together and was ready to start.
I passed about 12 volts through it and would get a decent meter readings whenever I swiped my hand in front of the feedhorn assembly. I was convinced that it worked.
Step 3: A Test Run of the Sun
I tried pointing the dish at the sun. As you can see in the picture to the right the meter was pegged. It only did this when the dish was pointing at the sun. I deduced that, "Yes indeed, it was picking up the sun." Note the dB knob turned all the way down. It seems the sun packs a mean punch!
Step 4: I Still See Radio Sunshine on a Cloudy Day
Next a meter reading when some clouds passed in front of the sun. Still a decent amount of signal but definitely not like the unobscured sun reading. Note that I turned the knob up a bit to actually see the signal. The meter shot back up once the clouds were gone.
Step 5: And So...
this isn't an awesome, peer into the unknown type of radio telescope. Right now it only sees the sun. I plan on trying it on the moon and some star systems a little later on.
Believe me there is MUCH room for improvement on this system. But it was good enough to teach me some basics and to strike my curiosity a little further.