Machine for making wooden offset dishes of various focal lengths

[polgyver]

How about that metalized duct tape?

Gee, isn' t there a telepathy ?
After cleaning (grinding) the dish, I was thinking about 12" wide aluminum kitchen foil and contact cement, when I found a leftover from metalized duct tape.
Was not sure it would be enough, but gave it a try.
Kitchen foil is 15 microns thick, and duct tape - 42 microns.

 

[Cosmo Blatz]

When did this site start asking "Are you sure you want to like this post"?) Never saw that before.
Now I'm not seeing the tool bar in the reply box. Maybe it's the 'noscript' app I just added to Firefox. But, I did allow scripts for this site! so hmmm. Going to bed.

Metalized duct tape. Forgot about that! Used that on my failed salad bowl reflector. Yours has a MUCH BETTER chance of working!

 

[polgyver]

Got this dish working, finally. Not much Quality percentage, though, as I did not dare to tinker with temporary, shabby LNBF bar.
Gonna try mirrors later, for checking the focal spot.
Pictures follow:

 

[polgyver]

Some update : annotated pictures below:

 

[Greenish Apple]

Neat polgyver. How wide/tall/deep is it?

GA

 

[polgyver]

Neat polgyver. How wide/tall/deep is it?

GA

The dimensions are on picture below.
I used 3 pieces of 4'x4' tile underlayer which is sold in Home Depot, about $13 for a sheet. I cut off 16" straps to get 32"x32" squares. Three squares were enough to cut rings and circles for one dish( 10 pieces ).
Probably the remaining 16" straps could be butt glued to make other 32"x32" boards.

 

[polgyver]

Please keep us up-to-date on your progress

Recently I made second wooden dish, its focal length is 150 cm. f/d = 1.9
14 pictures - below:

 

[pacificrim]

Super cool! Nice work!

 

[polgyver]

9 annotated pictures;

 

[Cham]

Looks like you need an adjustable scaler and feed horn for these long focal distances. Extending the feedhorn (tube) in front of the scaler would possibly accomplish this.

Also have you tried checking the alignment when the feed-point is off-center such as if using multiple feed points? Might be some areas where the reflections might be a bit tighter...

 

[Titanium]

Agreed on the need for a specialized scalar. The current f/d .5-.6 LNBF is likely illuminating 300-500%+ including the side of the house!

I had posted some papers on scalar design and calculations in an old thread. Will try to locate the link. Should be able to cut off the existing scalar and fashion scalar rings based on the extreme f/d.

 

[Titanium]

Found it. Good read! Check out section 6.4.3
http://www.qsl.net/n1bwt/chap6-4a.pdf

 

[polgyver]

Looks like you need an adjustable scaler and feed horn for these long focal distances. Extending the feedhorn (tube) in front of the scaler would possibly accomplish this.

Sound advice, in posts 30-32 Thanks, Cham and Titanium...
The scalar I made is -surely- shabby, but it helped with reception.
I wish I could learn more about designing such scalars, instead of trying intuitively with parts...

 

[polgyver]

Found it. Good read! Check out section 6.4.3
http://www.qsl.net/n1bwt/chap6-4a.pdf

Paul Wade is well known as researcher and experimenter in very high frequency communication.
I had this privilege to follow his professional advice.
It seems that values of higher L/D ratios still allow for more experiments and research.

 

[spongella]

Amazing polgyver, and a beautiful piece of woodwork. You definitely think out of the box. Good luck in perfecting the dish. Beautiful pictures too.

 

[TAZI MOHAMED]

Je suis enthousiasmé par une expérience similaire, mais je trouve cela difficile, en particulier la décoration faite à la machine sur le tableau.
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Pour les plats circulaires et ovales, j'ai eu des expériences avec eux mais ce type de plat est très différent.
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Il est nécessaire d'expliquer les étapes, par exemple les cercles dont le diamètre est l'épaisseur de la méthode d'installation.
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Les exercices ci-joints sont équivalents à eux?
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En général, comment calculer la distance focale? .
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Est-ce que ce genre d'autres plats est en termes de réception?
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Merci