Wanted chaparral skew motor

[frankviana]

Yes.. very dificult to send to Brazil. I live in Minas Gerais. I need to do ku band tests using my 5m dish motorized.

Here video tests using my hand:

60.7 MB file on MEGA

mega.nz

 

[Channel Hopper]

Thanks CH I did not think the corotor would cover 3.35 - 4.85 Ghz but its just out of band . Do you think I would get any better gain if I removed the first elbow on the corotor and bolted the Ku LNB straight onto the corotor in the same way I installed the C Band LNB I bolted it straight onto the corotor flange and not the elbow as we all know bends cause loss .

My response was for the Cband side of the corotor 2 and its flange but nevertheless......

Why not try with, and without the flange first ? Ys, there will always be a gain by removing a 90 degree elbow, but it might be negated by the shadow of the change in the waveguide depth, the standing wave ratio, plus the shadow of the LNB on the reflector surface.

You are always trying to walk when you can already run, fewer may keep up unless you can learn to slow down.

 

[John]

My response was for the Cband side of the corotor 2 and its flange but nevertheless......

Why not try with, and without the flange first ? Ys, there will always be a gain by removing a 90 degree elbow, but it might be negated by the shadow of the change in the waveguide depth, the standing wave ratio, plus the shadow of the LNB on the reflector surface.

You are always trying to walk when you can already run, fewer may keep up unless you can learn to slow down.

With the available gain from that 3.7 and assuming it is all set up correctly, worrying about the signal loss whether the elbow is on or off is just not worth it as you will just not be able to see the difference on 99.99% of received signals from the 3.7. My choice if that was mine would be to leave the elbow on as it makes the whole feed assembly more pleasing to the eye lol.

 

[subman]

Yes the dish is set up as if you connect up the scope if you scan move the dish from east to west you can see all the signals as you move across the belt since the polar mount has not had any maintenance it may require a small adjustment but seems ok I have however noticed that the neck of the feed is pointed about a foot above the centre of the dish as you can see in the picture but I am replacing the arms so that will all be reset up again . Ok on leaving the Ku elbow on the corotor .

 

[John]

Yes the dish is set up as if you connect up the scope if you scan move the dish from east to west you can see all the signals as you move across the belt since the polar mount has not had any maintenance it may require a small adjustment but seems ok I have however noticed that the neck of the feed is pointed about a foot above the centre of the dish as you can see in the picture but I am replacing the arms so that will all be reset up again . Ok on leaving the Ku elbow on the corotor .

>> Ku elbow on the corotor << - - ok my mistake, thought we were talking about the C band elbow but my statement would apply equally to both elbows with a reflector of that size

 

[subman]

Understood John When I installed the system I never used the C Band Elbow I bolted the LNB straight onto the corotor I would have done the same with the Ku band Elbow but that is held on by Torx screws but I now have a Torx screw driver set .When the replacement corotor arrives I will have a look .The update on the SMW LNB search is I think I have found one its a Type R Full Ku band .

I think while the dish is in bits I will give it a good rub down and respray with Cromadex Alu-Zinc + RAL 9010 Pure White I will just do the face only Oh yes and the Jack needs a rub down as well and respray as well . So lots to do .

 

[Terryl]

Be careful when you spray the Alu-Zinc coating on the dish face, make sure it's not pointing anywhere near the Sun, you can get a very bad burn, if you do this during the early morning then point the dish as far West as it can go, if done towards the late afternoon then point it East.

This time of year the Sun is almost directly in-line with the prime focal area of the dish,(in some locations and times) I allways had to warn the jr engineer assigned to clean the dishes, one got a very bad burn once, I had to come up with dish cleaning safety instructions, on the big 10 meter "C" band dishes we only cleaned them at night.

 

[Channel Hopper]

I would hope the dish is taken off the mount completely and put in the garage, wth all insects removed before spraying.

 

[subman]

Good thing you pointed that out guys . Well getting the dish into the garage may be a bit of a problem as it took 4 guys to lift over the garage roof same with the polar mount . Well the bottom half of the dish could do with a bit of TLC .

Most of the corrosion on the dish is in the lower half from 9 - 6 - 3 O/C maybe just rub down the lower half were the rivets but there is small patches of corrosion all over the lower half maybe rub those areas down then give them a spray with Cromadex Alu Zinc .

Looks for a replacement O ring and new set of bolts for the LNB .

Thanks again .

 

[Channel Hopper]

There are a number of different groove depths associated with he wr75 flange , try dropping the old seal in a pan of hot water for few minutes to rejuvenate it.

 

[subman]

Understood CH I think the screws and O ring require CPR due to the amount of corrosion , This is the LNB flange face already to bolt on . As for the respray on the dish I think I will just do the bottom half .

 

[Channel Hopper]

I had provided detail of penetrating fluids earlier , plus the time required for effectiveness earlier.

You are on a hiding to nothing with WD40 and 'day before' spraying.

 

[subman]

Well if I cant move the nuts I will just cut them off with the dremel as there not going to be used again . As for the replacement O ring and new set of bolts for the LNB I found this place .WAVEGUIDE FIXING KIT - AKD Sat-Comm .

As for the spraying the dish I think it will need a rub down in the lower areas of the dish as thats were the corrosion is if I do nothing and just install the new support arms give it 5 - 10 years and the corrosion might might start on the riveted areas .

 

[moonbase]

...
I think while the dish is in bits I will give it a good rub down and respray with Cromadex Alu-Zinc + RAL 9010 Pure White I will just do the face only...

The Cromadex paint used by Precision Antennas and Elite Antennas for a wet finish was Cromadex two pack polyurethane matt in RAL 9010. The Cromadex Alu-Zinc is probably a better option with regards to safety as it does not contain the isocyanates that are present in the two pack polyurethane matt paint.

 

[subman]

Yes well I was thinking these 2 paints .

 

[moonbase]

Yes well I was thinking these 2 paints .

Is the Cromadex Alu-Zinc Primer available in RAL 9010?

 

[subman]

Not sure MoonBase these 2 are the only ones I could find , Also looking for a WR-75 Flange O + Screw kit as the corrosion on the Ku elbow is very bad and I have a feeling the screws will shear off . Did find this kit but the screws look long and they have nuts . So I think this kit is for a in line Flange kit and the screws will fit but they need to be cut down a few mm .

 

[moonbase]

Not sure MoonBase these 2 are the only ones I could find...

I noticed the Cromadex Alu-Zinc Primer is indicated as being suitable for galvanised steel and steel but no mention of suitability for aluminium? I am guessing it would be suitable for aluminium as it is suitable for galvanised steel?

It might be cheaper to use something like Halfords Etch Primer if you expose the aluminium when rubbing down the dish. The Halfords Etch Primer could then have a RAL 9010 finishing coat applied on top.

I have attached below a few pictures of a Precision 1.5m dish that I restored to its original RAL 9010 colour using a spray can of Halfords Etch Primer and a tin of paint applied with a roller. The dish had been painted in some camoflague colours by the previous owner and my personal preference was to restore it back to it's original colour.
.

 

[RimaNTSS]

looking for a WR-75 Flange O + Screw kit

If you give precise dimensions of the O-ring and screws, I could find couple of set for you.

 

[subman]

If you give precise dimensions of the O-ring and screws, I could find couple of set for you.

Many Thanks Rimants for the offer of the O ring and screws its for a standard WR-75 flange . I will have a look at the spec sheet for this type of LNB but the screw kit I have found I think is for a inline flange because you have nuts from looking at your bowl I would think you must have 4 bolts there that would fit . I will have a look on the SMW web site or have a chat with SMW as screw and O ring are a standard I would have thought . Attached is the confirming the size . Seems there M3 Screws . Hope this helps if not I will contact SMW . But its a standard WR75 flange screws and O rings should be standard size .

Ok MoonBase Yes I can only assuming that Cromadex Alu-Zinc Primer is ok to Prime aluminium it should be its £30 a can , There is patches of bare aluminium already showing so I will just rub thoses areas down but it all seems to be in the lower half of the dish . What ever work that has to be done on the dish has to be done on the polar mount as it will not fit through the garage door is only a standard 7 foot wide single garage door and the dish is 12 Feet + . Yes I would think that Halfords Etch Primer maybe the best as its allot cheaper at only £10 a can .Thats a good idea use a roller not thought of that .