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Topic: Low-profile, reverse-focus Satellite Dish Mount - cheap and light! (Read 2 times) previous topic - next topic
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Low-profile, reverse-focus Satellite Dish Mount - cheap and light!
Yahoo Message Number: 58030
I recently discovered the concept of mounting a satellite dish upside down.  It lets me travel with a much smaller, lighter stand that is incredibly quick and easy to set up.  I love not having to haul that old metal tripod around in our 23.5 FL anymore.  The homemade stand cost me $10 to make and took about two hours to make (I'm not the speediest guy in the workshop ).  I've put details on my web site:
 http://home.earthlink.net/~wxtoad8/index.htm

Under "Lazy Daze Topics", choose LD Enhancements.

Ted H.
'02 FL   NE-12
Re: Low-profile, reverse-focus Satellite Dish Mount - cheap and lig
Reply #1 –
Yahoo Message Number: 58031
"I recently discovered the concept of mounting a satellite dish upside down. It lets me travel with a much smaller, lighter stand that is incredibly quick and easy to set up'

Ted

Have you used the dish, in the new configuration, for long? I'm a little confused. I always thought that the convex shape of the dish focused the RF energy to a central pick up point. Isn't the rear of the dish concave? It would seem that a concave surface would disperse the RF waves in many directions.
Maybe with the newer, more powerful satellites, concentrated focusing is not necessary. It might be more of a problem in higher latitudes (Alaska and Canada).
I need to take a closer look at a dish. I wonder is my neighbor would mind me climbing on his roof?

It sure is smaller, lighter and less prone to be blown around by the wind.
Good tip.

Larry
2001 MB
* Not to be confused with Larry W (3000 of my posts are actually from expert Larry W due to Yahoo transition mis-step)
Re: Low-profile, reverse-focus Satellite Dish Mount - cheap and lig
Reply #2 –
Yahoo Message Number: 58033
Quote from: Larry"

I always thought that the convex shape of the dish focused the RF energy to a central pick up point.

Larry,
 Take a look at the pic on his link. His dish isn't mounted "backwards"... rather it is rotated 180 degrees so that the bottom side of the dish is now on top. It is still pointed in the correct orientation.

David
Re: Low-profile, reverse-focus Satellite Dish Mount - cheap and lig
Reply #3 –
Yahoo Message Number: 58035
Quote
... His dish isn't mounted "backwards"... rather it is rotated 180 degrees so that the bottom side of the dish is now on top. It is still pointed in the correct
Most parabola dishes have the feed in the center and the rim of the dish is at right angles to the direction of the transmitter.  Digital TV dishes are of an offset feed type.  The feed is at the edge because only part of the full parabola is there; the rest is cut away because it is unneeded.
 Normally, this type of dish is mounted with its feed at the bottom and its face roughly vertical.  As a result of being only a partial dish (or an offset feed type) the point that the dish is aimed at is well above a line drawn at right angles to the rim of the dish (apx 45 degrees above?).

What Ted has done is to, in effect, turn the dish upside down and re-aim it at the satellite.  Because the dish's beam was roughly 45 degrees above the direction its feed was at the bottom, it is now roughly 45 degrees below where it is pointed when the feet is at the top.  This requires the dish to be moved from being roughly vertical to now being roughly horizontal to be still pointed at the satellite.

The only question I have is how the polarization of the feed worked out.  The microwaves coming down from the satellite are polarized and the feed horn of the receiver must be oriented correctly to receive them.  When the dish is reversed, it seems like the feed horn will end up 180 degrees from where it started and all will be well.  Is that what happened?
 How do you keep it from filling with rain (a western Oregon question)?

Linley
Re: Low-profile, reverse-focus Satellite Dish Mount - cheap and lig
Reply #4 –
Yahoo Message Number: 58110
Thanks, Dave, for answering Larry's question for me.  Yes, all that is "upside down" is the orientation of the dish.  If you look at that little tutorial I linked to on my web site, it shows how it works.
 Linley, I'm not an electronics wizard, so I have no clue about polarization.  But it seems to make no difference at all in the signal.  Yes, the feedhorn is 180 degrees from the normal, but it still works.  As for filling with rain, at least up here in New England, the dish is still tilted quite a bit, so that's not a problem.  We'll see what happens when we get to FL this fall.  There is a hole in the middle of the dish, so if it were really flat, it would drain, I guess.
 I'll be giving this thing its first operational in-the-field test tomorrow.  If there are any problems, I'll report back.

Ted H.
'02 FL  NE-12

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Re: [Life With A Lazy Daze RV] Re: Low-profile, reverse-focus Satel
Reply #5 –
Yahoo Message Number: 58154
Having not used this mount  I'd suggest drilling a few holes at the point the water pools.

Garry
Re: Low-profile, reverse-focus Satellite Dish Mount - cheap and lig
Reply #6 –
Yahoo Message Number: 58173
I promised a report: I set up the dish today in its first truly deployed situation - took me about 10 minutes  altogether to set it up and aim it.  I'm in love with it - no need to worry about levelness, since you don't use the elevation settings on the dish bracket.  I use the in-line signal finder gadget, and it was amazingly easy to move the dish up and down and slightly side to side after determining the basic azimuth.
 As for pooling water, at least up here in more northern latitudes, the dish is still tilted quite a bit - there'll be no water pooling in it.  We''ll see how it is down south this winter.

Ted H.

'02 FL  NE-12
 From: "Garry & Maxine Foster" garry.foster@...>
 Having not used this mount  I'd suggest drilling a few holes at the point the water pools.

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