Step Two: Modeling

I left you with three major pieces of receiver horn on the desk. Follow along as I make a fairly accurate rendering of this to house my hacked electronics. Let's start with the translucent cap. 

I was unable to get the horn's cap off that night, so I measured it in place.  

ReceiverCapV1.JPG

I left the inside corner sharp on purpose, I wanted to make sure this left me with the most simplified base for when I got the real one off... I figure I'll actually print/finish/cast this in a urethane resin. I'm not sure how PLA and Bondo will obstruct the radio waves. Next thing I sketched up was the Coax connector area.

CoaxJackV1.JPG

I intend on making this the actual connector for the receiver, as it fits both USB and Ethernet jacks (physically, holding them up), which is why I left all of the internals out. I'll have to see what will grant me the better physical jack connection. To Mouser! And Newark! Yeah... that makes a lot more sense... Don't use a USB-A connection... Go for Micro B or B or something smaller. Hindsight and all that. I should really just go for a single USB-C connection and call it a day. get a Micro B slot on the other for additional power or something. I can waterproof this stuff no problem, so that card is called already.  I shouldn't even be dealing with this now... Fool.  On a side note, this isn't 100% accurate, because there are little flares at the base keyways for about 2-3mm, but they only stick up about 0.5mm, so I just left them off.

Back to modeling, The only other thing I have left to model is the main body. I'm planning on making this, more or less as-is. There's the data pad, for the company sticker and all the major info, but I'll probably leave that off and just sharpie any relevant info onto the first few models. I'll make one on the side. That should work. So we'll start with that. One of the great things about making parts like these is the use of the "Mirror" function. this way I spend all of my time, making careful measurements of the one side, and then spend 30 seconds making the other. 

Side A, 

Side B, 

The only thing I have to do to this model is add attachment points for it, Case screws and electronics mounts, stuff like that. But a lot of that will be dictated by the electronics I install, which I have yet to start working on. 


Many Moons Later...

I've made lots of progress since I last updated this... I have designed and mostly fabricobbled together the mounting bracket, and have worked out most of the major components for structure and power. I'm still waiting on the stencils to come in, so after that, I should be all set to finish the major construction...

The basic support structure will be made out of some PVC DWV fittings and Schedule 40 Pipe, along with some custom bracketry. I've modeled the general idea in Revit: 

The Parts-list - so far - is as follows:

  • 90* 2" PVC Elbow
  • 45* 2" PVC Elbow
  • 2" to 1-1/4" FNPT PVC Adapter 
  • 2" PVC Coupling
  • 2" PVC End Cap
  • 2" x 10' (7'2" actually used) PVC Pipe
  • 1-1/4" x 3" Galvanized Pipe Nipple

Had I taken a closer look at the intended space, I should have just used a regular 45* Street Elbow, but I bought the parts on a whim and decided to wing it. Live and Learn I guess... Another thing to note, I had a lot of 2" PVC lying around, this could probably be done even cheaper if you used a smaller diameter pipe. I had two sections of pipe that added up to 7' so that's where that number came from. A single 5' length should bring you down by about $1.20 at my local parts store at the time of writing, disavowing sale prices. 

 

Step One, Refinishing

Unfortunately I do not have any pictures of the dish before I disassembled it, but I do have some during the refinishing process. I started by scraping off as much of the old peeling paint as I could. 

Then I hit it with the orbital sander loaded up with a 120 grit disk. 

I wasn't trying to get a mirror finish on this, I wanted to be sure I didn't see any of the edges of the old paint. A note, this only really worked because the sander is small enough, about 30% of the disk never really got used, as the concavity of the dish made the sander rest on the edges. To see an exaggerated example of this, Find a CD and place it in a cereal bowl, assuming you have a regular cereal bowl with a tapered edge, you should see how the disk only touches on the edge. the only real negative impact of this was that the paper "wore out" faster than normal. But I think the results of 2 disks speak for themselves.

The other parts I hand sanded and self-etching primed sans-camera.  I had a lovely bunch of swingers hanging from the garage ceiling in various places.

After the primer dried, I hit everything with a Rustoleum rust-stopping white spray paint. Now, looking back, I would have done things a little differently. I would have liked to take a day and use automotive paints for this, and if I ever have to re-paint this, I will. It definitely would have saved time on the dish, and would have given me some additional practice with the guns on smaller parts. Next time! 

Once the white finished drying, I sprayed it with some matte finish clear... after a google search just now, I feel like this may have been a slight mistake...

Radio waves are a type of electromagnetic (EM) radiation with wavelengths in the electromagnetic spectrum longer than infrared light. They have have frequencies from 300 GHz to as low as 3 kHz, and corresponding wavelengths from 1 millimeter to 100 kilometers.
— https://courses.lumenlearning.com/boundless-physics/chapter/the-electromagnetic-spectrum/

Realistically, the surface finish should show no real difference from matte to gloss coat, even at 1mm. Hell, I probably could've gotten away with the scraped galvanization, with some encapsulator on the rust-spots, if it wouldn't look like crap. I have to put this in view of the neighbors, and I have new neighbors, so I'd like to be friendly. 

Anyways, I primed and painted the dish as well, but I only cleared the back and edges, as I am waiting on some "finishing touches" to come in. I may re-coat the whole dish in a lacquer clear, if I wasn't an idiot and use enamel base-paints... ARGH!!! Alright, well... damn. I'll just clear it like the rest... I'll have to media blast this when the finish inevitably dies, then I'll use auto paint for it. 

Until those touches come in, I can't finish the dish properly. So I get to start modeling components. I have the original horn upstairs, and I did forget to take pics it before disassembling it, but here's what it looks like disassembled. 

About

I've written about it in some other posts that will pop up after this, but I have a lovely old ... I believe it's a Dish brand, Satellite receiver from my neighbor's house, that I want to turn into a Radio Telescope. I'm starting this page kinda late, as I've already nearly refinished it... but my documentation thus-far should be half decent. I just don't think I have any pictures of the pre-torn down dish. 

Let's back up, What is a "Radio Telescope?" Simply put, it's a tune-able radio antenna that listens to space. If you looked at a cutaway of a standard Newtonian Reflector telescope, you will see essentially a longer version of the Observatory at Arecibo, in Puerto Rico. My go-to example of a... (what do you call something that's above PHD level of commitment?) Really well known and high powered version of a Radio Telescope. Cornell University's Astonomy division has an amazing overview of how Arecibo works, you can read that excerpt here

 The basic cutaway of a Newtonian Reflector

The basic cutaway of a Newtonian Reflector

Now, there's another way to listen to the stars other than digging a Giant 305 meter (1000.66 feet) diameter dish into the mountainside:The Very Large Array ( no, I'm not kidding) is a 27 unit array of  25 meter (~82 feet) diameter radio telescopes. Now, the way this works, is once you compare the minute differences in distance, and do some fancy math and programming, the array acts as a single, much larger dish. What this allows for is a bit higher overall cost, but, you can track celestial bodies, thanks to their gearing just underneath the actual dish, as well as decreased maintenance and down time. as you don't need all of the dishes to be up and running at the same time, you can calculate out the missing dish to a reasonable accuracy should one be in for repairs. Arecibo, on the other hand, is a case of, when it's broken, none of it works. 

--[ For more information on why these kinds of telescopes are impressive and important, Watch this video on YouTube about pulsars, and go watch yet another amazing Zemeckis movie called "Contact" Starring Jodie Foster and Matthew McConaughey. ]--

Because the dish I have is pretty tiny, at less than a meter in diameter Long Ways, I intend on finessing this receiver first, then adding additional ones as I acquire them. Ideally you would want the dishes to all be the exact same size and all nine yards, but I think that, especially because I am super amateur on most aspects of this build, that I shouldn't have many issues with adding signals from different dishes. My receivers are probably going to be craptastic enough to not notice much of a difference. 

The general outline of this project is as follows:

  • Restore the dish
  • Model and print missing/modified casements
  • Create motorized equatorial mount
  • Build mounting solution
  • Build new Radio Receiver
  • Run power and data lines to indoor unit
  • Listen to other wolds on-demand

Onward to New Sounds!