Antenna's focal point - "le point G"

[skomedal]

That was some beam deviation @ 2meters.

Good luck with the Boresighter for rifles.

BTW how will you mount it the lnb holder?

Regards

 

[RimaNTSS]

BTW how will you mount it the lnb holder?

Will look for lathe-man to make adapter with outer diameter 40mm and inner hole diameter to firmly hold boresighter.

 

[skomedal]

Should do it.
Remember when it arrives to do the rotation test for beam accuracy.

Regards

 

[Trust]

I already did some tests some time ago . http://www.satellites.co.uk/forums/threads/lnbs-aiming-point.160762/
Made several Youtube movies , see Trustmie https://www.youtube.com/channel/UCXSc8WauhQ-oedsNAn4MILg
Tomorrow I am leaving home for vacation .
But when I am back I hope to read here where the G-point of this dish (dont know the brand) is , and make a test with the rotating laser to see if its the same as from the calculated G-point .
A-B 1010 C-D 940 mm , point E is exactly the middle 505 . (Strait line messeurments)
Tested that by laying the dish flat and draw a line along the edge and placed the dish the otherway . Its a geometrically oval .
E-G 76 mm
Placed tapeline in the dish , following the shape (total lenght 1030 mm) and switched on the laserpointer , checked it and adjusted it .
The spot was at 580 from the topside , then changed the direction of the pointer exactly to the edge on the topside .
Turning around shows that the spot did not reach the bottom side , 35 mm above .
Also missing the left and right side by 21 mm

 

[RimaNTSS]

Sometimes we relay too much on "what manufactured did and said" , it especially apples to how manufacturer made feedarm. Original feedarm not necessary holds LNB in focus.
Did you measure A-F and B-F, where F is Focus of antenna?
Distance B-G should be measured not on surface of antenna but as marked by green line on attached picture.


Wim! Do not worry, take your time during vocation. Do not forget to accomplish "special task".
We well try to not post too much stupid posts while you are enjoying Indian summer.

 

[skomedal]

I've ordered this Boresighter, waiting delivery. Should be OK tool.

This is loaded into the chamber of the weapon to be zeroed in, the beam thus traveling along the whole length of the barrel ( guide ) so no beam deviation along its length.

Not sure how this device will operate for your purposes without the barrel to guide the beam.

Sorry if this is a stupid post.

Regards

 

[RimaNTSS]

Adapter I am going to order to made will look like piece of barrel with outside diameter 40mm (diameter of LNB body) and internal diameter of the hole will be equal to boresighter's outside diameter. So, boresighter will be inserted firmly in this adapter and then placed instead of LNB.
I think it is also possible to put dust tape around boresighter till it's diameter become 40 mm. The result will be more or less same, just not so esthetically looking.

 

[skomedal]

Think your missing my point a .308 caliber weapon ( boresighter model you refer too ) barrel is longer and has more accuracy ( less beam deviation ) than dust ( think you mean gaffer ) tape.

Hope i`m wrong and wish you good luck

Regards

 

[RimaNTSS]

Barrel, of course, is long, but boresighter is only about 4cm long, so, it is really does not matter how long is barrel. Main thing here is how tight boresighter sits inside barrel and there is no play between them.

 

[skomedal]

Focus point!!!!!!!!!!!!!!!!!!!!!

 

[RimaNTSS]

Focus point!!!!!!!!!!!!!!!!!!!!!

Sorry, did not get you. Boresighter's laser lamp should be located exactly in Focus, if you meant that.

 

[Trust]

Did you measure A-F and B-F, where F is Focus of antenna?
Distance B-G should be measured not on surface of antenna but as marked by green line on attached picture.

You did not asked them before , and if I know them , I wont tell , your calculations must do that . so I can compare them .

 

[Captain Jack]

This is a little over my head! I kind of get it but need to sit down and work it out properly with the dish in hand.

 

[skomedal]

You can the theory with the offset dish g.

But I think you lack the practical insight to prove your theory.

Buying laser pointers that do not run true or laser boresighters that depend on weapon barrel length to concentrate the laser beam I think you can get near but still not get too the g on the offset dish.

Weapon barrel length impracticable and tape solution not guaranteed

There are laser boresighters that you put in the end of the weapons barrel but seems general consensus amongst weapon owners that they are a joke due too inaccuracy.

Will wait in anticipation for your results before I reply to this thread.

Good luck.

Regards

 

[RimaNTSS]

But I think you lack the practical insight to prove your theory.

First of all this is not my theory but geometry of offset antenna.
And secondly, knowing Focus and G point and pointing LNB directly from Focus to G is much better than placing LNB somewhere and pointing it anywhere.
Boresighters DO NOT depend on barrel's length and barrel DO NOT concentrate laser beam, that is nonsense.

Will wait in anticipation for your results before I reply to this thread.

Than can take long time, I am not in hurry and practical results not expected soon. Will miss you in this thread.

 

[skomedal]

Than can take long time, I am not in hurry and practical results not expected soon. Will miss you in this thread.

Will bump it weekly if no action

Regards

 

[RimaNTSS]

You did not asked them before

No, but hoped you will place LNB in calculated position but not where it accidentally got :mad:

 

[bim]

First of all this is not my theory but geometry of offset antenna.
And secondly, knowing Focus and G point and pointing LNB directly from Focus to G is much better than placing LNB somewhere and pointing it anywhere.
Boresighters DO NOT depend on barrel's length and barrel DO NOT concentrate laser beam, that is nonsense.
Than can take long time, I am not in hurry and practical results not expected soon. Will miss you in this thread.

Are lazor sights not the same as tele sights. The biggest problem here I see, I may be wrong, with a tele sight the tele sight is adjusted to a given distance and point of impacted. Therefore it is irrelevant if the sight is not true as this is done on the adjustments of the sight with the gun. Even if the barrel is not true it makes no difference as the sights are tuned into the barrel?

 

[sonnetpete]

I don't think Rima is intending to use a device similar to that used in laser sighting for a firearm. From what I can see, the laser device would fit inside the chamber of a rifle to check for the accuracy of it's barrel. Hence they are available in ammo sizes, E.G. .308.

 

[RimaNTSS]

From what I can see, the laser device would fit inside the chamber of a rifle to check for the accuracy of it's barrel. Hence they are available in ammo sizes, E.G. .308.

Thanks sonnepete! I am trying to explain this for last 20 or so posts, but probably my English is not good enough. Exactly like you said: boresighter is inserted in barrel instead of cartridge and laser beam shows where rifle is pointed. And this is not for hunting but to calibrate your optical device. So, when you point rifle to a target lets say 100 yards away and see whether your optical device showing you same spot. That means, when you remove laser boresighter from barrel and insert real round, point your optics to target and shoot, then you will get the target.
And main difference between usual laser-pointers for Power Point Presentations and rifle boresighter is that first one not necessary have body line completely parallel to laser beam. Rifle boresighters designed and made to both those lines be completely parallel. Of course, nothing is perfect.