Channel Master 1,2m issue

[RimaNTSS]

I've got couple of Channel Master dishes without feedarms. So, finally decided to make new feedarms, and also fix multifeed issue. Each LNB-holder (including central one) now adjustable in all possible directions.

 

[tamuin]

Quite a number of topics covered on this thread - neat stuff too.

Getting back to the focus issue, what do people think of applying a reflective film (HVAC metal tape or the auto store rear view mirror repair film) to several locations on the dish and using the sun to find the focus point?

 

[RimaNTSS]

For me, there is no need to find Channel Master's Focal point, as the position of this point is well known. I've made this collage for almost all (except 0.75m) CM antennas with all needed dimensions. Moreover, it is well known offset angle of CM dishes, therefore the position of the LNB can be set with the precision of 1mm.

 

[Magic Static]

Quite a number of topics covered on this thread - neat stuff too.

Getting back to the focus issue, what do people think of applying a reflective film (HVAC metal tape or the auto store rear view mirror repair film) to several locations on the dish and using the sun to find the focus point?

Polgyver has a few threads about using little mirrors for unknown dishes. Lots of good pics too
Checking dish's focusing with mirrors and magnets - another version

 

[Larry1]

My Starchoice 1m dish (made by Winegard) has the LNBF pointed below the centre of the dish. Attached is the fax from Winegard showing the measurements.
Maybe Channel Master can provide the information for the measurements of the requested dish.

 

[RimaNTSS]

Larry1 Thanks for this information. Nice picture from 1997. I must say that this is very seldom that producer of antenna gives such clear picture of the geometry of their product. Did they also provided an Offset angle of the dish? If yes, than all important information is there. TBH, I did not see that producers provide information about aiming point on the surface of the dish so precisely. And Channel Master, surely, one of them.
This way your picture is more understandable

 

[a33]

Did they also provided an Offset angle of the dish? If yes, than all important information is there.
View attachment 132547

If the 26.22 really is the G-spot distance, all important information is already there:
The dish height would then be 43.37, and offset angle would therefore be 23.22.

greetz,
A33

 

[RimaNTSS]

Agree with you a33 , but some companies (will not name them here) provide width and height of the working area but completely wrong offset angle. It is buch easier with Channel Master antennas, they all have 22.6* offset angle (for bigger mirrors there is even 2 digits after coma). I find offset angle very importante, as it allows to adjust LNB's position very precisely.

 

[Larry1]

Larry1 Did they also provided an Offset angle of the dish?View attachment 132547

The offset angle was in their general spec sheet.

 

[RimaNTSS]

And now I see some mismatch: Datasheet says that 1m antenna has dimensions 105x114cm, offset angle 24* and focal distance of 59cm.

I do not know how they get such an offset angle! Perhaps they mentioned antenna size including the edges?

 

[a33]

Perhaps they mentioned antenna size including the edges?

I guess so.
I guess the 39.4 effective aperture would mean the width. But even with that value, it doesn't fit the values of the first drawing of top string, bottom string, and effective focal distance, as I let my calculator calculate.

So again the specs given by the manufacturer are not fully consistent.
Or maybe the dish would not be parabolical/paraboloid?

greetz,
A33

 

[catamount]

Mine measures about 42 7/8 by 39 1/2 inches straight across each way