My homemade 3m parabolic radiotelescope

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Mario M.

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Aug 11, 2023, 12:40:26 PM8/11/23
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Hi

I always wanted a radio telescope. Ever since I saw movie "Contact" when I was around 10. Large dishes were really expensive so I decided to build my own. I settled on 3m diameter. 2m would also be fine, but I decided, when I'm making it I might as well make it 3m. It's F/D= 0.4 dish. 

I'm planning to listen to 1420MHz frequency, and I have a Nooelec SawBird amplifier for it. 

I didn't have a lot of free time to work on it, so this took about 1.5 years up to this moment. I decided to share some photos now that the dish is mounted on the mount and it actually looks like a radio telescope instead of looking just like a bunch of parts!

My dad helped me with welding and other stuff. The dish weights around 40kg.
montaza2.jpg

Better picture of the dish while it was on the ground. 2/8 of the wire mesh were temporary removed to allow for easier acces inside the dish.
montiranje_feedhorn.jpg

I took every precaution to make it as accurate as I can, but in the end I don't know how it will behave. Hopefully the wooden parabolic parts will be strong enough and not distort too much under weight.

It's located in a quiet little village in mountains of Croatia. 

B & MR Randall

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Aug 11, 2023, 12:52:39 PM8/11/23
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Your construction job is impressive.  Hope ypu get feed and radio together soon

Bruce Randall

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Mathew George

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Aug 11, 2023, 1:35:51 PM8/11/23
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Dear Mario,

It is inspiring to see your work. I wish you all success with your endeavour. It should not be hard to see first light, but it might take a while until you optimise your setup. 

All the best,

Mathew


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Anthony

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Aug 11, 2023, 1:42:10 PM8/11/23
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That's nice!!

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Mike

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Aug 11, 2023, 2:36:46 PM8/11/23
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Wow, that truly is a beautiful construction. Well done Sir. Please keep us posted on your efforts. This is very inspiring.

Mike Thompson
KG4JYA
Mikeasphere


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djl

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Aug 11, 2023, 3:29:17 PM8/11/23
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Very Nice!

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Michael Perkins

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Aug 11, 2023, 5:33:49 PM8/11/23
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Mario,

That is a fantastic job well done!
We look forward to seeing more as your project progresses. 

Michael
KB1PQS


On Fri, Aug 11, 2023 at 12:40 PM Mario M. <mariom...@gmail.com> wrote:
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Alex P

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Aug 11, 2023, 5:46:53 PM8/11/23
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Hello Mario,
Congratulations :it looks very well made.  
If the feed is tuned, the next step will be to adjust the dish<>feed spacing ..
Start with perhaps 3 cm steps and refine from there. 
Pick a bright spot in the MW and optimize the difference between cold sky and peak H1 readings.

Post some data when  you get all operational.

Regards
Alex KK4VB


Marcus D. Leech

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Aug 11, 2023, 5:58:16 PM8/11/23
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On 11/08/2023 17:33, Michael Perkins wrote:
Mario,

That is a fantastic job well done!
We look forward to seeing more as your project progresses. 

Michael
KB1PQS

I similarly echo those sentiments.  It is a thing of remarkable beauty.  Looking forward to some "first light" data!


fasleitung3

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Aug 12, 2023, 3:57:29 AM8/12/23
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Hi Mario,
Just like everyone else here I find this is excellent work. You should be very close to seeing first light.
Good luck and if there is anything where we can be of assistance just let us know.
Best regards,
Wolfgang




Mario M.

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Aug 12, 2023, 9:17:46 AM8/12/23
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Thanks for the kind words, it means a lot.

Yes, the feedhorn is about 70% complete. I need to install the antenna and solder the aluminium parts and that's done. Then digging out and putting a electrical conduit in the ground. I think I'll get first light in about 1-2 months.

Mario M.

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Aug 12, 2023, 9:18:55 AM8/12/23
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Thanks for the advice, I'll try that.

Lester Veenstra

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Aug 12, 2023, 10:00:51 AM8/12/23
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Mario:   Would you be willing to publish a drawing.  I would particularly like to see how the mount was designed.

Thanks

   Les

 

Lester B Veenstra  K1YCM  MØYCM  W8YCM   6Y6Y W8YCM/6Y 6Y8LV (Reformed USNSG CTM1)

les...@veenstras.com

 

452 Stable Ln

Keyser WV 26726 USA

 

GPS: 39.336826 N  78.982287 W (Google)

GPS: 39.33682 N  78.9823741 W (GPSDO)

 

 

Telephones:

Home:            +1-304-289-6057

US cell          +1-304-790-9192

Jamaica cell:    +1-876-456-8898

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Mario M.

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Aug 12, 2023, 10:12:32 AM8/12/23
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I don't really have a drawing, but I do have some close up photos. The base for the mount was the bearing from the car wheel. On top came a steel holder for a wooden pillars, and on it I put some other regular bearings for another axis. There's a cog wheel for future, when I put motors on it.

Forgive the junk on my garage shelves :)

mont3_2.jpg

mont3_3.jpg

stup3.jpg

Lester Veenstra

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Aug 12, 2023, 10:28:25 AM8/12/23
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Thanks

 

Lester B Veenstra  K1YCM  MØYCM  W8YCM   6Y6Y W8YCM/6Y 6Y8LV (Reformed USNSG CTM1)

les...@veenstras.com

 

452 Stable Ln

Keyser WV 26726 USA

 

GPS: 39.336826 N  78.982287 W (Google)

GPS: 39.33682 N  78.9823741 W (GPSDO)

 

 

Telephones:

Home:            +1-304-289-6057

US cell          +1-304-790-9192

Jamaica cell:    +1-876-456-8898

 

From: sara...@googlegroups.com [mailto:sara...@googlegroups.com] On Behalf Of Mario M.
Sent: Saturday, August 12, 2023 10:13 AM
To: Society of Amateur Radio Astronomers
Subject: Re: [SARA] My homemade 3m parabolic radiotelescope

 

I don't really have a drawing, but I do have some close up photos. The base for the mount was the bearing from the car wheel. On top came a steel holder for a wooden pillars, and on it I put some other regular bearings for another axis. There's a cog wheel for future, when I put motors on it.

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Dimitry UA3AVR

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Aug 12, 2023, 12:13:27 PM8/12/23
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Good luck to see first light ... nice work, Mario.

пятница, 11 августа 2023 г. в 19:40:26 UTC+3, Mario M.:

b alex pettit jr

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Aug 12, 2023, 12:42:43 PM8/12/23
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Mario,

Are you going run the 1.42 GHz signal via a long coax or install the SDR near the antenna and have the long run digital ?
What is the length of the buried conduit ?

Alex


On Saturday, August 12, 2023 at 11:17:01 AM EDT, matovin...@gmail.com <matovin...@gmail.com> wrote:


Thank you so much for all the nice comments. It means a lot :)

Regarding the feedhorn, It's about 70% done. What's left to do is to put the antenna and connector and solder the aluminium parts together. Should be done soon.

And then a nice workout - putting the power cable and its conduit under ground.

I'll keep you posted and until then here are some more old photos .


The mount


Soon-to-be-operational feedhorn
alu_feedhorn.jpg


Early phase of dish construction. I used a line to align all the parts together. This part of the build was a nightmare. It took so much time.


Closeup of the feedhorn mounting spot
prsten_nosac_feedhorn.jpg



Eduard Mol

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Aug 12, 2023, 2:11:41 PM8/12/23
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Amazing work, Mario, well done! That dish looks really good.

Looking forward to your first light and subsequent results.

Best,
Eduard



Mario M.

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Aug 12, 2023, 3:40:13 PM8/12/23
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I will have amplifier on the side of the feedhorn and SDR also very close, probably on the feedhorn too.
Conduit is about 50m long, from the house.

b alex pettit jr

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Aug 12, 2023, 4:05:52 PM8/12/23
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Hello Mario,

How do you plan to transfer USB data over 50m ? 

I found USB over Cat Cable Extenders work fine but radiate significant noise from the Cat  cable. 

I tried 4 different brands of USB over Cat Extenders .. the AV Star had the least noise, but still Way Too Much,
and the only solution I could find was to move it away from the antenna.
I moved the SDR and USB Extender ~ 7m away from the antenna using LMR 400 .

( There is 12V power in/out of the box to power the WD5AGO LNA and WideBand Amps on the antenna. )

Inline image


  >>   Perhaps you should run some tests before finalizing the design...


Alex

Nathaniel Butts

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Aug 12, 2023, 5:04:37 PM8/12/23
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Love it.  Gives me good inspiration for a future big dish.  Super interested to see your first signals.

USB to CAT can be problematic if wire pairs aren’t twisted, as alex said.  Not sure what you’re using to process the SDR signal, but if you digitize at the source that will help with the signal loss.

Thanks,

Nathan Butts
Wannabe Astronomer
Bowling Green, KY

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Mario M.

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Aug 13, 2023, 3:22:04 AM8/13/23
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Sorry, I didn't explain good enough. I will have raspberry pi in a (hopefully) waterproof enclosure on the dish pillar. That way I will only have 3-4 meters of USB coming from feedhorn to raspberry pi. I will control raspberry pi over wifi. I have a small wifi extender so I will use it.

Mario M.

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Aug 13, 2023, 3:24:21 AM8/13/23
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I'm interested as well. Do you think I would get anything if I point feedhorn (no dish) directly to the milky way? Just to test it before I put everything on the telescope.

Eduard Mol

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Aug 13, 2023, 4:09:58 AM8/13/23
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Yes, you will see the Milky Way HI signal with just the bare feedhorn.

Op zo 13 aug. 2023 om 09:24 schreef Mario M. <mariom...@gmail.com>
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b alex pettit jr

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Aug 13, 2023, 6:19:57 AM8/13/23
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Hi Mario,
Pre Test everything ... 

H1 Signal Levels are much lower than even the blackbody emission from room temperature objects.
 = You  need to verify the WiFi signal does not overload the LNA.
Inline image


1) Try your planned design.
 2) If there are RFI  problems, use coax and move the SDR to a location 'shielded' by the dish screening.
     Since the data will have been amplified by 40 dB,  few m of LMR240 will not affect performance.




Inline image

A useful tool to locate RFI sources is to make a simple 21cm long Loop Feed connected to
the LNA  and hold it near suspected sources.  ( any flexible coax to the SDR is fine )

Inline image


Regards,
Alex

Larry Mayfield

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Aug 13, 2023, 11:25:54 AM8/13/23
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Alex, great idea regards the loop antenna. I’m gonna make one!

But will make it so that I can use the actual hardware in the system so that  I will hopefully know how the system works together and then for bad places, and then I can do to experiment to reduce the RFI.

Sound?

 

Larry

Pahrump

 

From: 'b alex pettit jr' via Society of Amateur Radio Astronomers <sara...@googlegroups.com>
Sent: Sunday, August 13, 2023 3:19 AM
To: sara...@googlegroups.com
Subject: Re: [SARA] My homemade 3m parabolic radiotelescope

 

Hi Mario,

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Douglas Decker

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Aug 13, 2023, 11:30:07 AM8/13/23
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I like Alex had to do some extending. Some information that may help others.

The above shows my rough one line.

Systems working fine.


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Marcus D. Leech

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Aug 13, 2023, 11:35:44 AM8/13/23
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On 13/08/2023 11:30, Douglas Decker wrote:

I like Alex had to do some extending. Some information that may help others.

The above shows my rough one line.

Systems working fine.



An approach that is becoming more economical is to have SDR+computer in a shielded box behind the dish--so you
  only have a few m of cable between the LNA output and the receiver.   Then carry your ethernet connection from the
  computer via fiber -- 1Gig  fiber bridges are now fairly cheap.   Aggressively decouple the power feed going into the
  computer box and make sure your fiber goes through the smallest possible hole in the shielded box.

We sorta-kinda use this at the CCERA observatory in Carp, ON.   The LNAs are at the feedpoint, then there's about 10m
  of cable that feeds our 4-channel SDR in the elevation cabin behind the dish, then a 10G fiber going to our computer
  downstairs.


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Mario M.

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Aug 13, 2023, 11:58:28 AM8/13/23
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Hopefully the wifi doesn't interfere with the amplifier and SDR. Otherwise I won't be able to use my raspberry pi zero which only has wifi, and doesn't have ethernet port.

Nathaniel Butts

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Aug 13, 2023, 12:05:18 PM8/13/23
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If it does, this may help. 

Ethernet/USB HUB HAT Expansion Board for Raspberry Pi 4B/3B+/3B/2B/Zero/Pi Zero W/Pi Zero 2W,with RJ45 10/100M Ethernet Port (Based on RTL8152B Chip) and Three USB Ports,Compatible with USB2.0/1.1 https://a.co/d/36QwBV7

I made a router/hub for traveling with one and I like it. 

Thanks,

Nathan Butts
Wannabe Astronomer 
Bowling Green, KY
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b alex pettit jr

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Aug 13, 2023, 12:06:34 PM8/13/23
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Hello Larry,

 Exactly . 
 It is best to see how Your System responds to the RFI

Alex

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Mario M.

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Aug 14, 2023, 2:14:21 AM8/14/23
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Good idea! That or USB extender.