Attempting to use an unknown dish for FTA

[KE4EST]

Yeah, I started to post a reply earlier. I was thinking...HUH??

 

[Doorguru]

Yeah, I started to post a reply earlier. I was thinking...HUH??

Yes.. I just now posted a reply debating the dish sizes, but then deleted it when I realized what happened.. Maybe my old timers disease is kicking in!

 

[Brct203]

Oops!! My mistake.. I got my posters mixed up!! I was looking at polgyver 's post and the picture of his dish and got it mixed up with your post!! I even mention his nice photo in one of my replies.. I apologize for all the confusion..

no worries It's all good. Hopefully you'll be able to get that dish working properly. I have 2 of them, and they are decent dishes. I have one fixed on 123W with its original LNB (not so good in general but works really well for KBS World, not sure why), and the other one I had for a while on 34.5W but it was too small. I had used one for 125W at some point but that was also a bit undersized. Definitely very usable on the stronger satellites.

 

[danristheman]

Dual stacked lnbs you have to scan vertical side. Not as sensitive lnbs as a pll but work all right in a pinch.

 

[Doorguru]

no worries It's all good. Hopefully you'll be able to get that dish working properly. I have 2 of them, and they are decent dishes. I have one fixed on 123W with its original LNB (not so good in general but works really well for KBS World, not sure why), and the other one I had for a while on 34.5W but it was too small. I had used one for 125W at some point but that was also a bit undersized. Definitely very usable on the stronger satellites.

I clamped the LNB on the arm and tried to get it to match your numbers.

The best I could do is 19" and 26 1/4" or 20 1/2" and 27 3/8", in other words when I got one of your measurements right, the other was off. The single hole next to the two mounting holes you mentioned measures 21 1/8" and 27 3/4" . That is where my LNB is mounted in my original picture from post #1. This dish originally had 3 LNB's. Every time I think of how I dropped them in the trash can it makes me feel sick!!

But never-the-less I will figure it out when I temporary mount the dish to the huge pine tree out front. The spring clamp will allow me to slide the LNB up and down. It will be time consuming trying to hit the three adjustments at once, but with a little luck.. I have done it many times before, but did not have to deal with a focal point. The tree is solid and will not flex unless there are high winds. I will mount it on the lower trunk.

 

[Brct203]

Dual stacked lnbs you have to scan vertical side. Not as sensitive lnbs as a pll but work all right in a pinch.

yes they are a pain to use - simply because so far I have not found any receiver that has the matching LNB option. So I set those as "standard LNB" with the LO at 10750, which works fine for Vertical, but the displayed frequency for horizontal is completely wrong. Still, they work. Also the LO drift on the ones I have is about 7-8 MHz, so blind scanning is a must.

However, that dish and feed assembly has a very interesting use: put the FSS (11.7-12.2) LNB on the circular feed, and aim that at Anik F3 @119W to see what's there. It's an easy way to get a circular feed in the "standard" Ku band.

 

[Doorguru]

I know that everyone here has their method of finding a satellite, but I just wanted to update my progress and explain how I did it. It might just help someone who is new to this hobby someday!

I leveled and mounted the dish to the pine tree. I left the elevation as it was when it was used for Dish Network. I guesstimated the LNB position/skew and clamped it on with the spring clamp. I hooked up the tone meter and swung it west. Got a loud tone at what turned out to be 121 degrees west. Normally I would do a scan to see what satellite I was pointing to, but Dish Network told me on their test screen. "You are viewing Orbital 121 test screen." This satellite happens to have two transponders with the same or close to the same frequency as 97 west, which was what my meter was set to. I then tweaked the LNB position. The optimum spot turned out to be where I had it in my picture at post #1 of this thread, 22.5". I originally determined this by using the formula, f = ( D * D ) / ( 16 * c ) I was surprised that the formula worked for a dish like this. I used the widest diameter for the formula. The position happened to be the first single hole from the end of the LNB arm. The location of the LNB appears to be very forgiving.. a half inch either way had no affect on the signal. Knowing which satellite I was on gave me an idea as to where I would have to point to get to 97 west, so after raising the elevation, I eventually hit my target satellite with a decent signal of about 60. I did a scan and got about 120 channels using the portable meter. This will more than likely increase when it gets connected to a receiver as will the signal strength. It did the last time anyway. I think I will try adjusting the skew by rotating the dish. This will allow the RG connector to point down and be more out of the weather. I don't know if doing that will affect the signal strength though.

It's nice to have the portable meter with the screen, but without that cheap tone meter, it would have been a lot harder and time consuming!

 

[danristheman]

Old sonicveiw boxes used those lnbs but those recievers were used for theft of service.

 

[KE4EST]

Glad to see you got it Doorguru! However, I would consider dropping a pole and concrete in the ground. That tree will give you years of grief. Will keep you tinkering though.

 

[Doorguru]

Glad to see you got it Doorguru! However, I would consider dropping a pole and concrete in the ground. That tree will give you years of grief. Will keep you tinkering though.

Oh, this is temporary just to set the focal point and see how good of a signal I can get with a dish like this. It is probably the only place on this property that can see the horizon without having to install a pole. I will remove it from the tree and try to find a permanent location for it. Then point it to another satellite and use a diseqc switch. I already have 97W with the dish shown in my avatar.

Before removing it though, I will search for that additional satellite.

Anyone know of another strong satellite, preferably towards the west, with some decent channels?

 

[Doorguru]

Old sonicveiw boxes used those lnbs but those recievers were used for theft of service.

I didn't know that, but I use to be a pirate back in the day!

 

[a33]

I originally determined this by using the formula, f = ( D * D ) / ( 16 * c ) I was surprised that the formula worked for a dish like this. I used the widest diameter for the formula.

Well, that the PF-dish equation "works" for a dish like yours, would be an exaggeration, IMHO.
But it might bring you in the neighborhood of the focal distance, that is right.
I've seen enough dishes where the LNB phase center was not exactly at the focal point, that "worked" anyway.


How is the present LNB-position, as compared to the two lengths Brct203 mentioned?

From the center of the plastic surface of the linear feed (square wave guide which is centered on the arm while 119W circular is a bit to the side), I measured 26 1/4 inches to the upper edge of the dish, and 20 1/2 from the bottom edge.

Greetz,
A33

 

[Doorguru]

Well, that the PF-dish equation "works" for a dish like yours, would be an exaggeration, IMHO.
But it might bring you in the neighborhood of the focal distance, that is right.
I've seen enough dishes where the LNB phase center was not exactly at the focal point, that "worked" anyway.


How is the present LNB-position, as compared to the two lengths Brct203 mentioned?


Greetz,
A33

I was using the spring clamp so I could slide it all along the bracket and that position that I chose was as good as it got and I already had a hole drilled, so I bolted it down. If you read my previous post you will know that I could not make those distances Brct203 mentioned work. He also mentioned in his post that the same first single hole from the two original LNB monting holes was the focal point that he used previously on the dish pictured in his post.That was the position that worked.

 

[a33]

Well, you wrote you had two options, but you didn't say which one you chose.

The best I could do is 19" and 26 1/4" or 20 1/2" and 27 3/8", in other words when I got one of your measurements right, the other was off.

BTW Looking at your picture, it looks like your LNB is aiming rather high on the dish. It should be aiming below the center of the dish!
But maybe I'm deceived by the picture angle.

greetz,
A33

 

[Doorguru]

Well, you wrote you had two options, but you didn't say which one you chose.





BTW Looking at your picture, it looks like your LNB is aiming rather high on the dish. It should be aiming below the center of the dish!

But maybe I'm deceived by the picture angle.



greetz,

A33

I chose neither one.. This was explained in the thread. Maybe you missed it.

Brct203 said:

AND I QUOTE:

"I have used that dish with a LNBF and the same bracket as you are using, and found that the existing hole (the next one after the 2 holes that held the original feed) works well for attaching that bracket. You can see the mark left by that bracket on the arm on the picture below. "

END OF HIS QUOTE


The LNBs currently on his dish are not mounted as quoted above. They are mounted at the dimensions he told me.

"26 1/4 inches to the upper edge of the dish, and 20 1/2 from the bottom edge."

Those two values would not intersect at my LNB. That is why I didn't use them. I used the first single hole, as mentioned before in this thread.

This reply to you, by me, also explained it:

"If you read my previous post you will know that I could not make those distances Brct203 mentioned work. He also mentioned in his post that the same first single hole from the two original LNB mounting holes was the focal point that he used previously on the dish pictured in his post. "

As far as the LNB height itself, none of the pictures shows it, but I dropped it about an inch lower using the up and down bracket adjustment.

Look at this picture from post #1. The arm is sitting pretty low. I tried sliding the LNB back and fourth from the dish and even tilting the LNB down. The signal never got any better. This is how this dish has always worked, even when it was Dish Network. Has a strong signal now and did back then.

 

[a33]

The LNBs currently on his dish are not mounted as quoted above. They are mounted at the dimensions he told me.

"26 1/4 inches to the upper edge of the dish, and 20 1/2 from the bottom edge."

Those two values would not intersect at my LNB. That is why I didn't use them.

Yes, I think I miss/missed your point.

I would go for the best possible match to those two values that Brct203 gave, as you can deduct from my earlier post. Regardless of holes in the arm.

But I don't seem to be able to understand exactly what you are doing.

Greetz,
A33

 

[Brct203]

DoorGuru,

I need to add that while I used that dish with the bracket bolted in the hole that I mentioned, I eyeballed the position of the LNBF so that it visually matches the position of the old feed and fine-tuned it for performance but did not measure the position of the LNBF. So it could be that it was also a bit off for me too.
One thing worth trying is having 2 stings attached to the top and bottom rims (with a binder clip for example) with a mark at the lengths that I indicated, and where they meet when both marks are aligned would be the position of the front of the old feed. position the new LNBF so that it's close to that point. Arrange that it can still slide in its holder so that you can adjust it for best signal