Patriot 3.8 Commercial Dish strut length ?

[john_robot]

Hi!!

I have Patriot 3.8 Commercial Dish. The struts that came with dish is seems to be like for Multibeam Satellite Feed System.

So if I want to hook-up Bulles eye II what length struts should be ?

 

[SatelliteAV]

Which model? There are several 3.8m designs.

Since you have the current struts, it would be helpful to measure the focal point to the multi feed center position for your reference.

 

[john_robot]

The basic one with AZ-EL Mount

http://www.norsatwa.com.au/prod03.htm

 

[FaT Air]

The struts that came with dish is seems to be like for Multibeam Satellite Feed System.

Being it's an Az-El mount. I'd call that a 'bonus'. Don't have to 'fashion up' a multi satellite solution as it's already there. If only interested in a single satellite, just use the existing center feed placement.

 

[SatelliteAV]

The specs list the focal distance to be 57.625" (1.46m). Is this the measurement to the center position of the multi feed feedhorn mount?

Subtract the depth of the dish from the focal distance and measure the distance between the two leg mounting points then divide in half. Use standard geometry for an unknown triangle side. a2 + b2 = c2. You will need to slightly adjust the length to adjust for the scalar mounting.

If my suggestion is wrong, please someone correct...

Agree with FaT Air. No need to redesign. Use the multi feed mount for a single or add additional positions in the future.

Please post photos of the multi feed.

 

[john_robot]

Here is what I am trying to do. I want to use Pendragon's dual ortho system with this dish. And more I want to track all east to west satellites. So I removed Az-El mount and designed navigator mount for it. pls check the pic 1.



The issue is Same dish has different focal distance mentioned in manuals and on web sites. So I'm not completely sure what the exact value is. But one thing is for sure that the struts that came with dish is for Multibeam feed. pls check the pic 2 below (this pic downloaded from the net)


Unfortunately Multibeam wasn't came with the dish. Only the 4 struts received with the dish so I am not sure how to use it with Bullseye II.?? However I do have a same Multibeam feed with me that I bought few years ago. So what do you guys recommend ?

 

[FaT Air]

Well, you could calculate the F/D and focal length.

View attachment 86915
Then understand that some 'modification' to the focal length may be required as there's unforeseen measurement errors. But it should be close enough to get something, then proceed to 'tweak'.

 

[Anole]

keeping it simple, ...

...I want to use Pendragon's dual ortho system with this dish.
And more I want to track all east to west satellites.
So I removed Az-El mount and designed navigator mount for it.
. . .

Unfortunately Multibeam wasn't came with the dish.
Only the 4 struts received with the dish so I am not sure how to use it with Bullseye II.??
However I do have a same Multibeam feed with me that I bought few years ago.

The struts that came with dish is seems to be like for Multibeam Satellite Feed System.[FONT=Verdana, Arial, Tahoma, Calibri, Geneva, sans-serif] [/FONT]

Your question is a little unclear, but let me propose this:

If you have the struts for the multibeam configuration shown in the picture, wouldn't it be easier to use those existing struts and just fabricate your own mounting plate like the one shown?
All you need is its diameter.
And I'm sure you can locate a drawing of it on the Internet.

 

[FaT Air]

Some things to 'look at'

Originally Posted by john_robot
...I want to use Pendragon's dual ortho system with this dish.
And more I want to track all east to west satellites.
So I removed Az-El mount and designed navigator mount for it.

Referring to your picture 1
It appears that it is still an Az-El mount. Just with an actuator to adjust the elevation. Azimuth adjusted how? An Az-El mount will not adjust the skew as the arc is tracked. Only a polar mount will accomplish this. A dual ortho does not have electro/mechanical means of adjusting the skew. So as you move across the arc, the only way to adjust it is to manually twist it in the scalar.

 

[john_robot]

Referring to your picture 1
It appears that it is still an Az-El mount. Just with an actuator to adjust the elevation. Azimuth adjusted how? An Az-El mount will not adjust the skew as the arc is tracked. Only a polar mount will accomplish this. A dual ortho does not have electro/mechanical means of adjusting the skew. So as you move across the arc, the only way to adjust it is to manually twist it in the scalar.

On my dish mount the Azimuth actuator isn't installed yet. But when installed it will look like this. However now I am bit confused becoz one guy in my area told me that this mount need 7 degree angle ? is it true ?

 

[john_robot]

Your question is a little unclear, but let me propose this:

If you have the struts for the multibeam configuration shown in the picture, wouldn't it be easier to use those existing struts and just fabricate your own mounting plate like the one shown?
All you need is its diameter.
And I'm sure you can locate a drawing of it on the Internet.

I have the multibeam mounting plate and struts for it. But I have seen that several places multibeam feedhorns where connected without any scalar ring; never seen multibeam feed with scalar ring. Also in your mod you have used feedhorn with scalar ring; so that is why I thought of looking alternative way to hookup it.

 

[SatelliteAV]

On my dish mount the Azimuth actuator isn't installed yet. But when installed it will look like this. View attachment 86958 However now I am bit confused becoz one guy in my area told me that this mount need 7 degree angle ? is it true ?

You dish is not a polar mount, so the declination angle would not need to be calculated. The vertical actuator will aim the dish directly at each satellite position. What type of actuator controller(s) will you use to position the dish? To FaT Air's question... What controller and mechanical servo will you use to set the feed polarity/skew angle for each satellite? I also am not aware of any manufactured or available device available for adjusting the dual ortho.

 

[john_robot]

You dish is not a polar mount, so the declination angle would not need to be calculated. The vertical actuator will aim the dish directly at each satellite position. What type of actuator controller(s) will you use to position the dish? To FaT Air's question... What controller and mechanical servo will you use to set the feed polarity/skew angle for each satellite? I also am not aware of any manufactured or available device available for adjusting the dual ortho.

I am going to use two V-BOX 10's to control actuators. For polarity Teflon. Skew angle for each satellite ? do I really have to adjust skew angle for each satellite?

 

[FaT Air]

do I really have to adjust skew angle for each satellite?

For optimum performance, Yes. Although you could probably fudge until it degraded too much. Don't know how much of the arc that would 'cover' but guess maybe somewhere between 5 and 10 satellites (10 to 20° of the arc) before an adjustment were absolutely necessary. (Just a guess)

Could put your location in at dishpointer.com and read what the skew is for different satellites across the arc.
Think you'll see polarity is skewed as you move across the arc (but polarity remains 90° to one another).
Think the 'allowance' you could fudge the skew will change with each satellite. This because of the relative strength of the transponder of interest and also if there's any transponder on the opposite polarity and if somethings on an adjacent satellite.

For polarity Teflon

Huh? Please explain.
Polarity is either vertical or horizontal. You shift the probe in the feed 90° or select another probe that's 90° offset from the other.

A polar mount only requires 1 actuator and automatically adjusts the skew. AzEl requires some other means of adjusting skew.
Polarity is selected by the receiver LNB voltage (LNBF or ortho [with it's LNB's 90° to each other] and multiswitch) or by a servo on a polarotor(mechanical movement of the probe)
Here's a picture of a proper polar mount, where the difference between the polar angle(the Latitude angle) and that of the dishes face(or mount ring) would incorporate that 7 degrees. It's the difference between the two. The declination. Declination changes with Latitude.
This picture is with the dish looking 'true south'.

In conclusion: think it would be worth a bit of work now to do a polar mount for a couple of reasons. Less to break down, 'down the road', (Only one actuator) and ease of operation.(No need to somehow adjust skew)
Hope that didn't ramble so much it confused.

 

[Anole]

This does not compute

I want to use Pendragon's dual ortho system with this dish.

One for linear and one for circular, I presume?
(if not, please spell it out for us)



A polar mount solves so many problems you've created with independent motion.
I'd say it was time for a re-think.
.

 

[john_robot]

My location is Sri Lanka. pls see the pics . Dual ortho system I was thinking that I can use it for H and V.