V boxes, talk to me!

[aceb]

I managed to get the 1.2 Precision PF up this evening (I'll post up some pics if anyone is interested) complete with homebrew brackets to hold the C band feed but I've hit a bit of a snag. The original installer not only welded the PM to the top of the patio mount but cut off one of the actuator arms, as the previous owner was only interested in Middle East and Asian traffic the dish covered 75E to about 18W with no problem. Unfortunately it only gets as far as about 45W before the actuator hits minimum extension so I 'm off to find a welder tomorrow and move the arm to the other side of the bracket.

For testing I've just connected the actuator to a 12V PSU but obviously this isn't going to work once I'm sat back indoors so I need a V box, do they vary much in performance or quality. The MOTECK V BOX II and Technomate super box III look identical and I've also found the Superjack V box II and the V-BOX 400 (GBOX). Any recommendations on a particular unit?

One quick question on lining this thing up, I've read a couple of threads where it talks about setting the mount up square so the dish is at the top of the travel then go and find 1W by rotating everything by hand before locking it off. I might be having a hard of thinking moment here but shouldn't the mount be squared up, the dish driven to 1W then rotate everything to peak the signal or is it such a small difference that it can be fine tuned out later on? That reminds me, I need to find a Ku C120 LNB as well, expensive hobby this satellite stuff!

 

[Vipersan]

...Hi m8 ..
Its a question of whatever works best for you really ..

My prefered method ..since I tend towards the western arc ...and those sats in particular.

I first square up the Dish to the polar mount ..

Then set the polar offset and declination roughly as specified in the manual for the assembly ...

Then calculate or use the sun if its available to set the whole assembly to true South ...ie top of the arc ...which would be slightly off with regards to 1W ...
fully retract the actuator ( remember mine is on the left side of the dish as I face it) ....
loosen the dish and swing it westward to meet the retracted actuator ...and attach it ...
Power up the Vbox and set the western limit ...
drive the actuator arm ...to full extension and set the East limit ...
I usually set the mechanical limit within the actuator motor assembly a couple of clicks within those limits so as not to run the motor to the endstops..
In theory I'll never reach the Vbox set limits after this ..

At this point the dish should roughly track the arc ..

Then its a case of driving to 1W ...chosing a transponder and peaking the polar offset for max signal ...
Then driving to your extreme west satellite ..and tweaking the declination for max signal ...
Then back to 1 West to repeat any max signal adjustment with the polar offset ..then back to extreme west bird and repeat again with declination adjust ..
Ad infinitum...until you're happy with it ..

Providing you set the True South position accurately the dish should now follow the arc ...both East and West of true south ...

Remember V boxes don't contain stored positions ...so you then have to enter each sat you find manually ...and store it.

Always keep a hard copy list of satellite position/counts ...for future reference ...
In case anything moves ...or you simply forget.

Hope this makes sense..
It may not be the best way to do it ...but its always worked for me ..

You can calculate true south from tables using a compass ...but if the sun is available ...at a specific time of day ...solar noon...the shadow cast ( shortest length) is a useful tool to align with as you can mount a stick off the polar mount ...or use cross wires stretched accross the dish face as an indicator ..

rgds
VS

...oh ..and yes ...please post up some pictures of you newly refurbed dish ..
;)

 

[Vipersan]

...Hi Paul ..
A quick diagram ...much simplified ...showing what I consider to be the most important first adjustment ..

Its based on my assembly ..
Adjustments will vary according to type ..
rgds
VS

 

[Vipersan]

..Got to go open the shop in a few minutes ..
But here is another quick diagram showing the stretched crosswire method ...
You need to be ready ..
You need to have clear sunshine ...and the whole assembly locked in a line ..pole ...polar mount...and dish face ..

You need to wait for the specific time ...ie solar noon ..then rotate the whole assembly around the pole until the crosswire shadow bisects the dish centre ..
Then lock it up ..
You now have True South ..and adjustments will then be easier ..and more accurate..
rgds
VS

 

[Burnham Beech]

I prefer the software of the Moteck over the Gbox. They both work ok for me.

 

[aceb]

Thanks for the diagrams VS, I missed my window today as the mount was still at the welders but I've put it and am getting some results *If* we see any sun over the next couple of days I'll do as you suggest, until I've got the positioner sorted out I'm in no rush to get it perfectly aligned and bolted up anyway. I'll explain more in a new thread, it deserves one lol

Thanks for the reply BB, good to know.

 

[Huevos]

Any recommendations on a particular unit?

As I said in the other thread get the Clarke-Tech as it has double the resolution of any other V-box. Also with the Clarke-Tech you set due south to zero and going east it counts down -0001, -0002, -0003, etc, which makes a lot more sense to me than counting down from 999 to some meaningless number.

If you are in Eastbourne you don't want 1ºW at the top of the arc, otherwise you are going to go off as you go down the arc. Also, for a big dish "90 - latitude" will put your tracking out by almost 1º by the end of the arc so you need to do the proper calculation for that and if possible set it with a digital level.

 

[Vipersan]

As I said in the other thread get the Clarke-Tech as it has double the resolution of any other V-box. Also with the Clarke-Tech you set due south to zero and going east it counts down -0001, -0002, -0003, etc, which makes a lot more sense to me than counting down from 999 to some meaningless number.

If you are in Eastbourne you don't want 1ºW at the top of the arc, otherwise you are going to go off as you go down the arc. Also, for a big dish "90 - latitude" will put your tracking out by almost 1º by the end of the arc so you need to do the proper calculation for that and if possible set it with a digital level.

The Clarke Tech sounds impressive Huevos ..and if I didn't already own 2 V boxes ..and was in the market for one ..I'd certainly consider buying one.

As to you're other comment about 1W at the top of the arc ..
I totally agree ..and I suspect Aceb already knows it ..
I think he's going to use my crosswire method to accurately set TDC (True South) ..eventually .... but until he installs a Vbox to drive the dish ..
I believe he's itching to have a little fun and experiment.
Who can blame him .. ;)

rgds
VS

 

[Burnham Beech]

Can you explain this double resolution trick, the Moteck moves the 36v motor one pulse at a time and I can't see how you can better that.

It does need to have south set to 1000 and I agree that the vBoxes that set south to zero are more logical, but you get used to that.

 

[Huevos]

Can you explain this double resolution trick, the Moteck moves the 36v motor one pulse at a time and I can't see how you can better that.

The single count is only counting one state, i.e. it only counts when the reed switch closes. The double count counts both states, i.e. when the reed switch closes and when it opens.

It does need to have south set to 1000 and I agree that the vBoxes that set south to zero are more logical, but you get used to that.

When you send the Clarke-Tech to zero it goes to due South. When you try to send the others to zero they send the dish off to the east and never manage to get to zero because the software or hardware limits don't allow it, or even worse no limits have been set and something breaks.

 

[aceb]

As I said in the other thread get the Clarke-Tech as it has double the resolution of any other V-box. Also with the Clarke-Tech you set due south to zero and going east it counts down -0001, -0002, -0003, etc, which makes a lot more sense to me than counting down from 999 to some meaningless number.

If you are in Eastbourne you don't want 1ºW at the top of the arc, otherwise you are going to go off as you go down the arc. Also, for a big dish "90 - latitude" will put your tracking out by almost 1º by the end of the arc so you need to do the proper calculation for that and if possible set it with a digital level.

The Clarke Tech appears to be badged as a V-BOX 400 (GBOX) in the UK if it's the same model, I can't find too many people selling it but one of the forum sponsors Sat-shop do, at a good price too. Eastbourne isn't very accurate really, in reality I'm not much more than a stones throw, literally, from the Meridian.