Evolution of a home weather satellite station
"Tom, you've got too much time on your hands!"
-- Comment often heard from friends
One day I was surfing the web looking for pictures of the last solar eclipse and I came across Dale Ireland's web page (It's all your fault Dale!) and saw his pictures that he had there. Facinated by the simplicity of the equipment needed to do this I thought "Hey, that's very cool!...I can do that!", so I started researching this mysterious APT stuff on the web and came up with many different web sites on the subject.
This section of my web site is a description of how I got into this and includes image examples so you can see how they have improved as my equipment improved.
Radio Shack Pro-38 scanner - I found that I already had a radio that could receive the 137 Mhz frequency the satellites were on. I'll turn it on and see what I can hear. Wow! I can hear something out in Earth's orbit, I need to build an antenna!
Turnstile Antenna - I found some plans for a simple turnstile antenna from my searches on the internet. I built them using Geoff Chester's plans that can be found here: Web page. I live in a condo where there are antenna restrictions (arrggh!!), so I had to do this carefully so the neighbor's don't see it.
Results - This is the first image I got. It is from the Russian Meteor 3-5 satellite. At first I thought the twisting was due to doppler shift, my antenna, or possibly aliens? Later I found out that this was normal since the satellite was having some problems.
(Click image for full size)
Improvements - The image was kind of gray with speckles where the whitest part of the clouds should be (also notice the horizontal nulls across the image). I then modified the scanner to widen the bandwidth. I removed the IF filter and put in a .01uF capacitor. Much better!
(Click image for full size)
Radio Shack Pro-2038 Scanner - I went to a nearby hamfest one weekend and came across an almost new Radio Shack Pro-38 scanner. I couldn't pass this up at $50, and it also coverd the 137 Mhz that I needed.
Image results - I did the mod to this scanner and found that the images were 150% better, and MUCH sharper! I am now getting some sharp, but very narrow images. My clear horizons are very narrow. Hey, I can see Washington state now at least!
(Click image for full size)
Pre-Amp: I bought the Hamtronics pre-amp and connected that up to the base of the antenna in hopes to lower my horizon so I could get taller images. That helped, but there are still those irritating nulls.
Hamtronics pre-amp
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QFH Antenna - I read that there is an antenna called a Quadrafilar Helix (QFH for short) that isn't supposed to have any nulls. After further research I found a fairly easy design made from coax and some supports that are about 2 feet tall. That could fit in the attic, the neighbors would NEVER know! I put one together, attached the pre-amp, crawled around in the fuzzy attic insulation and came up with much better results.
QHF plans - Download
Results of amp, radio and QFH - NOW I'm finally getting somewhere! I am now getting some great images. I still have a little problem with some crosstalk from the local air traffic control getting in now and then, but overall pretty good results. Also, I am never quite able to get the gray scale quite right, plus a little problem with the bright white clouds now and then. Best of all, the nulls are gone! Other than a little noise from the nearby power lines, I'm very happy with the results.
(Click image for full size)
Hamtronics R139 - Ok, I guess I'm serious about this new hobby of mine. I now bought a dedicated radio for the satellites now. I'll put the IF filter back in my Pro-2038 and restore that to normal scanning use, and possibly put my other radios up for auction on Ebay. Now the results from going from the Radio Shack to the Hamtronics were similar to going from the Pro-38 to the pre-amped QFH! I now get excellent coverage (without the pre-amp now!), low horizons, great colors, and super sharp images!
(Click image for full size)
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