Installing the button hook and LNB onto dish

[tonydix]

I have almost completed the reassembly of my 24ft diam dish. I now need to install the lnb onto the button hook and then attach it to the dish.
I am a bit confused about the orientation of the button hook . Would the offset on the button hook be in a vertical plane if the dish was pointing at the horizon ? Does it Matter or will the servo motor cope with any orientation ?

What voltage should I apply to the servo motor to check its operation ?

Access will be difficult when the dish is raised onto its tower so I want to check out as much as possible before it is raised. Thanks for any help

Tony

 

[esteveW]

Button Hook Orientation

I don't believe the orientation of the button hook matters since you will be rotating the LNB feed horn for to the correct angle for polarity. Refer to you feed horn procedure.

In my opinion, the only safe way to check the servo is to hook it to your sat. box.

For what it's worthFrom Chaparral Corotor manual) Input to servo: 5 VDC @ 500 mA, Standard TTL logic and calls for pulse of .8-2.2 msec with a rep. rate of 17-21 msec.

Steve

 

[tonydix]

Thanks for the response. In my case the Chapparal feed horn is rigidly bolted to the button hook so no rotation is possible. The button hook is supported by 3 radial legs which have to be fixed to the arms of the dish by screwing. So it seem orientation of button hook offset wil be important !!
Tony

 

[tonydix]

Here are 2 pics :-

 

[esteveW]

Button Hook Orientation

Your Chaparral feed horn is mounted in the Scaler ring which is bolted to the button hook or side mounts. The Scaler ring has set screws which can be loosened for both rotation (oriention) or distance from the dish center. This is the way my Chapparral is mounted to the button hook (no side braces. Wish I did to assist in keeping it centered.).

Steve

 

[tonydix]

I dont seem able to get the photos inserted DUH !! but here is the URL


Picasa Web Albums - bigtone


If I look inside the throat of the feedhorn I see a bent piece of wire. When connected to the box this wire moves thru about 45 degrees when you move from Odd to even channels and the skew control makes minor changes in the position of the wire.
While looking up the feedhorn with the LNB vertically above the feedhorn the wire moves from about 4am to 8am as if it were a clockface.

I still need to know what postiion this wire should be in when I am looking at .the horizon There is no ajustment possible on the feed horn. The button hook connects to the dsih thru a flange at the center and is supported by 3 radial arms which are spaced at 120 around the dish supports I therefore have six possible ways of postioning the button hooh and therefore the LNB on the dish.

I need to know which one is correct

Thanks for any advice

Tony

 

[esteveW]

Button Hook Orientation

That feed horn is different from either of mine. One of mine is a Corotor II Plus and the other is just a feed horn with a C-band LNB and servo. However both have the same scalar ring mounted to to the end of the feed horn with allen set screws. On the side there is a graduated scale that the scalar ring is set to according to the f/D ratio.

Yours is a Chaparral but not a Corotor model. Your scalar ring is cast as part of the feed horn assembly.

To orient the Corotor model, there is a template that you make/use to do this alignment but I don't see how it would work on your.

I think you will have to go with, watching the oriention of the wire loop inside the feed horn throat or make not of the blue box possition when you play with H/V on you box.

Sorry I can't be of more help. I'm very new at this myself and just finished orienting the Corotor on my second dish.

Perhaps someone else know another trick.

Steve

 

[trinity13]

This one has a darker background in the notch (the yellow/first one was hard to see when I downloaded it).

 

[tonydix]

Thanks very much to Trinity13 for the template. Can someone explain exactly what is the Polar Axis as mentioned on this template. Is it the same as vertical and so the servo should be pointing at about 10oclock on a clock face.
Thanks for this help from an aged newbie
Tony

 

[Lak7]

With the Dish at it's highest point in the Arc, it would be 12 o'clock.
The Polar Axis is the point on which the Dish rotates East & West.

 

[esteveW]

It is straight up. However, make sure that your dish is aimed due south at the time you setting this. If it is over east or west then what appears to be vertical won't be true vertical, due to the declination of the dish.

If you can manage it, take a felt tip marker and put a reference mark in the top edge of the dish for future reference. On my solid dish, I' fortunate that the button hook is exactly vertical and I can use that for my reference.

Steve