Phlatwound Takes Over Care and Feeding of the Birdview Spoon

[phlatwound]

Thanks to all of you for your thoughts and suggestions. In my free time yesterday I did what any frustrated SatGuy who has been stumped by an oddball dish would do...moved my outdoor testing equipment about 10 feet and hooked it up to another dish.

The pic below shows the Spoon pointed at, errr...umm...receiving signals from 93W, and the BV prime focus solid is locked on 58W!

One of the pics is taken from above, looking down on the mount/wedge/reflector, it illustrates how the angles are interacting.

That parabola calculator is pretty cool Mr. Air, I had never seen one that did offset dishes.

I definitely need to determine the offset angle of this beast, it would make sense to me that the angle of the big wedge between the mount and reflector would be equal and opposite to the offset angle of the dish. That should have the dish looking in the same direction that the mount is pointing...but that doesn't seem to be the case.

Here (link) is another pic of a Spoon, notice it is also oriented 180 degrees opposite of mine, and both of the other pics I have found have the logo oriented the same, whereas my logo is 90 degrees off of those 2.

http://www.satelliteguys.us/c-band-...39-birdview-lovers-check-out.html#post2460879

 

[gabshere]

i'm rethinking my assesment and i don't know if you will like it .

 

[phlatwound]

i'm rethinking my assesment and i don't know if you will like it .

Would be glad to hear whatever you think.

Even if I can't get it to track the arc at worst I have proven that I could use this dish as a "movable fixed" dish for C or Ku-band...and did I mention it just looks cool?

 

[gabshere]

ok i'have review most every post here at satelliteguys on the Spoon and yes in my searches i found out that Birdview copyrighted that term " Spoon"
or maybe i should say the copyrighted "Birdview Spoon"

ok i need to set up parts so we know what i'm talking about in reference to the BVS
motor mount
wedge
dish
spoon

from pics i've reviewed Freds wedge (tag on wedge ) is on the right side ( from back of dish) Lonewolfs wedge tag is on the left.

i and i'm guessing here that the wedge is the difference between a east of mississippi west of mississippi type mount
i suspect that a west of the mississippi type mount needs the tag on the wedge to be on the left side.

dish the dish to me looks the same in all pictures (well almost) both ads have the logo in about the 10:45 - 11 o' clock range ( spoon top strut is even with bottom of logo)
when lookin at pics of take down ( at original setup site ) the logo is at about 9:30 with the spoon center strut centered on logo

on the ads the spoon top strut is even with bottom of logo , i can only speculate the dish being made in Kansas that it is the correct configuration for a west mounted BVS

now is this a ku dish that been modified to c band ?? ( i think fred posted that it was ) but in both ads the lnbf looks like the same old dual lna that i have from my normal BV something like lna 2020 .

also how does setting the spoon affect the dish readings ?? left side mounted centered or right side mounted ??
i guess you have the guinea pig and get to try these theories

 

[gabshere]

yes one thing you have to consider your close to tracking the arc now

but we don't know if thats the original configuration.

 

[phlatwound]

yes one thing you have to consider your close to tracking the arc now

but we don't know if thats the original configuration.

Actually I am nowhere near tracking the arc as it stands, I was raising or lowering the dish at least a degree or so AFTER I moved it with the motor.

Not sure what you mean by "original configuration", but I do think the motor mount/wedge/dish/spoon are configured as they were where it resided in St. Louis. And btw, that was within probably 20 miles of the Mississippi. And the way it is configured is 180 degrees rotated from the 2 "magazine" pics.

Even if the theory that you rotate the dish according to where you are located, like you do with a linear actuator holds true, if it is like a polar mount, that just affects how far you travel on the eastern or western portion of the arc...i.e. it doesn't affect the tracking, just the limits of mechanical motion.

The reflector is symmetrical. the motor mount is symmetrical, the spoon (feed support) can only be installed in one position, and the wedge can only be installed in one orientation on the reflector.

Maybe I didn't understand what you were getting at but I don't think the location of the tags and logos have any bearing on the assembly, I think they were just randomly placed on these pieces...and whoever put the logo on my reflector did it on a "Monday", and/or got fired soon after!

And I do believe these dishes were intended for C-band analog use, I don't think Ku was a big consideration.

Appreciate all feedback, keep it coming!

 

[Magic Static]

The way I look at it. Since you can't find any declination adjustment, it was ordered for location in the USA one of four or five declination adjustments determined by the wedge installed on the back of the dish, which also included the offset angle. The dish was found on it's side, but it needs to be installed as any normal offset dish. The side mount makes no sense at all. Since the dish was not properly installed at the first known location, we can't assume it was supposed to be where it was found. Without any information from the manufacturer, we can only reverse engineer it(measure the angles) and determine what latitude it would work the best. You have a real puzzler there, but don't over think it.

 

[FaT Air]

I'm pretty sure the present configuration is correct, as for many years(since at least since the late 80's) there's been one in use near me. Never did stop and talk but whenever I did drive by, the dish would be in a different position(up until a few years ago) .
Happened by there about a month ago, and the BV Spoon is GONE! Nothing but grass.
( that dish was the inspiration for putting my 1.2 sideways for 30W )
Take a look at the mount, is there anything, a mark(?) that would suggest "align this" for zenith? Anyway around it, I think I'd be pluggin' in numbers into that program to hopefully get the offset and proceed from there.
3D geometry wasn't my strong point in school, but with enough time, could figure out most.
In the back of my mind -- I have a feeling -- that the wedge shaped mount does not align with the long dimension of the dish.-- Is that possible?? with the polar axis set to your Lat?? and the dish affixed with the long dimension of the dish E-W???
Geesh, I hope that's understandable.
Well that's the 20 minutes I have today, G' nite.

 

[toucan-man]

Happened by there about a month ago, and the BV Spoon is GONE!

Could we have a moment of silence, please.

 

[phlatwound]

The way I look at it. Since you can't find any declination adjustment, it was ordered for location in the USA one of four or five declination adjustments determined by the wedge installed on the back of the dish, which also included the offset angle. The dish was found on it's side, but it needs to be installed as any normal offset dish. The side mount makes no sense at all. Since the dish was not properly installed at the first known location, we can't assume it was supposed to be where it was found. Without any information from the manufacturer, we can only reverse engineer it(measure the angles) and determine what latitude it would work the best. You have a real puzzler there, but don't over think it.

Thanks for your input MS, appreciated.

Here's a few more pieces to the puzzle that you may not have yet. The Birdview mount has approximately 5 degrees of declination built into it (the top half that attaches to the dish sticks out a little further than the bottom half). I have heard that there is also a fine declination declination on some mounts but I can't find it on any of mine, and as I understood it it was only good for a small fraction of a degree in adjustment.

I don't think there is any doubt that these dishes were designed and manufactured to be installed in the "sideways" position only. Besides all the pictoral and anecdotal evidence of same it is mechanically impossible to install the wedge/reflector on the mount in any other orientation due to the bolt patterns. The only reason I was able to install it vertically before was we drilled holes and installed nuts to be able to rotate it 90 (or 270) degrees from the position I found it in.

I am not really understanding how to measure the offset angle using the strings, but I did get some numbers for the parabola calculator which I will post below.

Definitely a puzzler but I don't believe I will overthink it, my thinker doesn't work good enough to do that.

 

[phlatwound]

Here are some numbers for the parabola calculator, if someone that has it installed could run them through I would appreciate it, can't get the program to install on my PC. Might be interesting to plug in a Ku Frequency also to see how it affects the numbers.

Frequency XXXX MHz
Large Diameter 100 in.
Small Diameter 84 in.
Depth 10 in.
Distance of deepest point from bottom edge along large axis 45 in.

That last number (45 in.) could have been is +/- 2", there is so little curvature I just tried to average it out.

 

[phlatwound]

I'm pretty sure the present configuration is correct, as for many years(since at least since the late 80's) there's been one in use near me. Never did stop and talk but whenever I did drive by, the dish would be in a different position(up until a few years ago) .
Happened by there about a month ago, and the BV Spoon is GONE! Nothing but grass.
( that dish was the inspiration for putting my 1.2 sideways for 30W )
Take a look at the mount, is there anything, a mark(?) that would suggest "align this" for zenith? Anyway around it, I think I'd be pluggin' in numbers into that program to hopefully get the offset and proceed from there.
3D geometry wasn't my strong point in school, but with enough time, could figure out most.
In the back of my mind -- I have a feeling -- that the wedge shaped mount does not align with the long dimension of the dish.-- Is that possible?? with the polar axis set to your Lat?? and the dish affixed with the long dimension of the dish E-W???
Geesh, I hope that's understandable.
Well that's the 20 minutes I have today, G' nite.

Very understandable, thanks.

I agree that the sideways orientation is correct, the only other possible orientation (as maunfactured) is 180 degrees from where I have it now. And I think that flipping the dish 180 degrees would just mirror whatever errors I am seeing to the other (east/west) side of the arc.

There is no way that wedge can be installed where it is not aligned with the long dimension of the dish, the bolt pattern will only allow it in one position.

When I had the dish in the vertical position and tracking 20-some degrees on either side of TS I think my elevation bar was at somewhere around 56 degrees.

 

[FaT Air]

How did the focal length "measure up' to the calculated Focal Length 44.72 in.
(Edge of dish closest to the feed to the feed)
offset calculates to 26.56° which would mean if the dish is face is looking 26.56° away from apex, the dish is really looking at apex- zenith satellite. Think it should be close enough to get the polar angle set to to your lat. an find it. Fine tune from there.
FWIW- Think puting the feed on the west would make getting the Atlantic satellites easier, or possible.

 

[gabshere]

if i gathered correctly from the picture the motor is at basically center ( has the same amount of gear teeth on each side ) so it should make a eastern arc turn . it just looks awkward

Phlat if it was pointed at 58 would it almost touch the ground ?

is the spoon arm adjustable ? i see it has a support rod is that ajustable ...

 

[phlatwound]

How did the focal length "measure up' to the calculated Focal Length 44.72 in.
(Edge of dish closest to the feed to the feed)

I measured about 38" to the edge closest to the feed, and about 92" to the edge furthest from the feed.

offset calculates to 26.56° which would mean if the dish is face is looking 26.56° away from apex, the dish is really looking at apex- zenith satellite.

That figure (26.56) looks plausible because the fixed part of the mount appears to be looking about 10 degrees east of zenith, and I think the wedge on the back is counteracting about 15 degrees of the offset: 26.56 - 15 (wedge) = approx. 10 (fixed mount facing direction).

Think it should be close enough to get the polar angle set to to your lat. an find it. Fine tune from there.
FWIW- Think puting the feed on the west would make getting the Atlantic satellites easier, or possible.

Thanks for running the numbers through the program, I was unable to install it on this ancient laptop I am running with now.

I don't understand why the frequency is entered as one of the variables. Isn't a dishes focal point and offset angle determined by it's physical dimensions and construction?

Did you enter a C-band frequency, and does the output change significantly if you enter a Ku-band frequency?

 

[phlatwound]

if i gathered correctly from the picture the motor is at basically center ( has the same amount of gear teeth on each side ) so it should make a eastern arc turn . it just looks awkward

Phlat if it was pointed at 58 would it almost touch the ground ?

is the spoon arm adjustable ? i see it has a support rod is that ajustable ...

Yes, the mount is at apex, and I am receiving signal from 93W (my true south) in that picture.

That is what I was ciphering out in my post just above this one...mount is centered (same amount of gear teeth on both sides) but it is facing about 10 degrees east of true south, which would be about right if the dish face is looking 26 or so degrees east of true south, the wedge is 15 degrees and the offset angle of the dish is around 26 degrees.

Not sure how close to the ground the dish would be if I ran it over to 58W, I just went to 87W when I was testing. Next time I play with it I will attempt to go further east with it.

And no, the feed support (spoon) is not adjustable and that little brace arm is not adjustable, it is fixed at that length and position.

Thanks to both of you for your input!

 

[FaT Air]

Pretty sure the freq is entered to calculate gain and nothing more. I used 4Ghz and 12Ghz on my CM 1.2's and the only diff was the gain numbers. Offset & feed spacing to top and bottom lip came out the same.(guess for the Spoon should be E & W lip to feed)

 

[phlatwound]

Pretty sure the freq is entered to calculate gain and nothing more. I used 4Ghz and 12Ghz on my CM 1.2's and the only diff was the gain numbers. Offset & feed spacing to top and bottom lip came out the same.(guess for the Spoon should be E & W lip to feed)

Of course, gain is what that is for. I got tunnel vision thinking about angles and inches, didn't even think about the gain.
And yes, E & W lip for the Spoon for those measurements.

I hope to take another run at this critter this weekend. The angles we have discussed make sense, and have been somewhat proven with the testing I have done so far.

Since I am receiving signal from my true south at 93W with a polar axis elevation of about 34 degrees, it may be that I need to add 3 + degrees of declination (my latitude is 37.14) to get this thing to track. I hope not though, can't imagine that would be required if I have it assembled properly and they worked from the factory.

 

[FaT Air]

37 would lower the dishes "look angle" from the present 34. So a slight bit of elevation adjustment an then of actuator, and azimuth (one way or another) to keep it seeing 93W. Might require many 1/4 degree increments. When the elevation is at your lat, and still seeing 93, see if it tracks. Just wishful thinking, as it sounds easier than what I'm sure the actuality will be.

 

[FaT Air]

Parabola calculator calculations.
Height and width determine the offset angle.
With that, the depth and placement of the "deepest" depth measurement determine the focal length and placement of the focal point. Effective area and frequency is used for gain calculations.
On getting it to track:
Think I brainstormed how:
The dish is 'looking' at zenith when the point on the dish, opposite the LNBF, is at it's highest point from the ground.
Polar axis angle will/should be your latitude, Dish face (perpendicular) will be offset degrees towards the side with the LNBF when "looking" at zenith.

EDIT: To "visualize", stand off to the LNBF side of the dish and draw a line from the LNBF side(centered) to the furthest point of the dish, and continue this line off into space. But 'bend' the line 90° minus the offset degrees towards the face of the dish.