Gibertini Polar Mount (for 1m dish) advice please

[femto]

Hi, It's been quite some time since I used my Gibbi on its polar mount, as, in another post I made, I'd had a little problem whereby the dish was being removed and due to the weight and length of the pole it was on, hit the ground rather briskly and was made unservicable.

I'm about to go to my local satellite shop to pick up a new dish and polar mount (yes, the mount got bent too ) and I can't remember some details about the mount.

Specifically:
What sort of azimuth range can I realistically expect when using this polar mount with a 12 inch Superjack?

What is the reason for the mount being supplied with two arms? By that, I mean the arm that fits on the top of the mount, where the eye of the jack is bolted through.

I'm going to use the settings on the old mount and dish bracket to set the new one up. I think if I do that, I'll only have to twist the whole sha-bang around the ground post a touch to trim it all up, if I'm right?

Ta very much.

 

[femto]

Ah well. I put the jack back on the old bent one and it looks like I might get 50e to 50w but we'll see what occurs when I set the new one up tomorrow...assuming the weather is kind that is. :-)

 

[Sandybob]

I have never understood why the 1.0m gibby polar mount has the lever arm in two pieces, maybe cost/pakaging! and have read about lot of people getting confused about it and why they have to be bolted together. I have a 1.2m gibby polar mount here in the box and the lever arm is in one big long piece. I think most polar mounts will only travel about 70° max anyway depending on the design.
Any chance of a few pictures while your putting it up?
Good luck

 

[femto]

Yeah, sure. It's going to be easy to take some pictures because I'm mounting it on my ground post.

Yesterday, I fitted the 12" jack on the old polar mount again and ran it backwards and forwards using a Superjack EZ-6000 positioner I have, in order to set the hardware limits and it seems that the full mechanical travel of the mount is possible. More so in fact, as before I reset the mechanical limit for when the jack is extended, the two parts of the mount met and slightly jammed up.

On further inspection of the two arms, the angle of the bolt-hole is different. Possibly, one arm is for use in northern latitudes and the other is for areas closer to the equator. Most probably to make sure the actuator's eye can be bolted to the flat surface of the arm over a large range of latitude settings. I dare say they could be bolted together to give the system more leverage and resolution but I don't think it's actually the manufacturer's intention. Anyway, you'd lose range of movement without using a longer jack. Say an 18 inch instead of a 12 inch.

I'll take some photos and edit this post...or reply again when I've got them.
I'll be setting off to the satellite shop soon to pick up the new Gibbi and polar mount...if they've arrived from their supplier! I better ring them up first I suppose.

 

[satelliteman]

The 100cm polar mount will travel around 80° using a 12 inch jack. Depending on which side you mount the jack, care has to be taken not to drive round too far and buckle the mount trying to get it back. Set your actuator travel and position and clamp on the mount to suit the arc required. It should be also noted the polar mount for the 100cm will accept a mast upto 54mm only. The two arms are supplied but you use the one to suit the installation on site.

 

[femto]

That's what I thought after I puzzled over it. One arm seems to fit and the other seems way off. At the moment, I have the arm on the left, with the jack fully retracted to send the mount to the east and extended for westerly directions. Is one side better to use than the other or is it just whatever is the most convenient side to mount the motor?

 

[satelliteman]

Both arms will fit but depends on polar axis angle [mount inclination] setting and position of jack as to which suits best. You mount the jack to suit the site installation.

 

[Sandybob]

I thought the two short arms had to be bolted together (busy looking for an embarrassed icon) but that was only what I read as I have never had a 1.0m polar mount, only the 1.2m which is a bit different. The other polar mounts I have had only had the one arm.
Best of luck.

 

[satelliteman]

I thought the two short arms had to be bolted together

No, they don't bolt together. There are pictures on another board where someone has done just that.

 

[femto]

Thank you to everybody for your helpful comments.

I'm all ready to go. I've built the mount up indoors, using my old, bent polar mount as a guide for the angle of the dish backplate, as unfortunately, the declination adjustment on the polar mount, where it joins with the dish backplate, doesn't have a scale...so it's guesswork for that.
Assuming I've worked out my latitude setting on the polar mount right, I've set it at about 54º (correct me if I'm wrong please).

So, if I find Thor at 1º west, peak the signal up by adjusting the declination of the dish and swivelling the polar mount on the ground post, the arc should fall into place. Am I on the right lines there? I suppose it'd be best to leave the actuator off the mount while I sort it out?

 

[satelliteman]

Pretty much along those lines. You also need to account for around 1° on the polar mount prior to alignment having a longitude of -1.7524°. It'll be a small tap on the mount in the correct direction.

As for declination, this will be made by lowering the dish elevation onto your due south satellite 0.8W/1W. Use either a meter or the receiver to get your alignment. Below is a picture of my old dish indicating of rough idea of the dish elevation/declination offset from the polar axis angle.

Once aligned, move the mount by hand and check the arc then add the actuator last.

 

[femto]

Right, here's what it looks like.
I've got 36º east to 37.5º west. I can probably squeeze a little more out of the hardware limits actually but I'll leave it be at this stage I think.

 

[satelliteman]

Unless there's anything you want beyond then I would leave.

Be sure the limit switches switch off long before the actuator's mechanical hard stop is reached.

 

[Lazarus]

Right, here's what it looks like.
I've got 36º east to 37.5º west. I can probably squeeze a little more out of the hardware limits actually but I'll leave it be at this stage I think.

Great pics ............ the first two in particular are almost a Tutorial: Might come in handy if my TD110 causes premature death of its DiSEqC H-H Motor.

 

[Sandybob]

Very nice install, neat and tidy.