Solid Spun Aluminum 8.5 footer - Maybe Regency

[linuxman]

Started working on tuning this BUD Thursday afternoon. Spent about 4 hours just getting everything working properly. I soon realized that I would need an A/B video switch because of all the back and forth between the Legacy and Traxis receivers. Very slow start on Thursday.

Went to the Rat Shack and picked up a switch Thursday evening, and started again on Friday morning. My calculations were only about a half inch or so off, and F/D appears to be around .40 at least that is where I am getting my best signal.

This dish is like the Birdview in that it has a built in declination of about 4.5 - 5 degrees. For my location, I need about 5.5 degrees. So for today, I am going to have to fight the two top bolts loose on the rectangular mount and make some shims to fit between the mount and the dish to give me the extra declination I need.

The A/B switch is a life saver, but it is still a struggle fighting with the Legacy for skew and movement while watching the SQ on the Traxis.

The numbers so far are not very impressive, but I think will improve with the declination.

G15 (133W) C-Band several TPs - 70% SQ I haven't been able to tune in the California Channel yet. Analog is maxed out on the Legacy meter, but that doesn't mean much for digital. I get the CA channel at 45% on the Pansat/BV combo.
G11 (91W) C-Band TP 1 - 80% SQ This is at 90% on the PS/BV
G11 (91W) Ku-Band Bell test card - 45% SQ - 75% on PS/BV
G17 (74W) Ku ONN is at 80% SQ - maxed out on the PS/BV
AMC6 (72W) C-Band NASA digital is at 70% SQ - about the same on PS/BV
AMC6 (72W) Ku I am having some trouble pulling C-Band through the Ku side. I think I have setup the wrong Ku satellite format for that one. Will have to work on that.

As I said, the numbers aren't real impressive on the Traxis. I am not yet used to it's meter, and it may be a little more conservative than the Pansat. It's threshold for picture is higher than the Pansat. Seems to pixelate a little below 45% SQ.

I was so tempted to just unhook the Pansat and use it for the fine tune, but if I don't get used to the Traxis, I never will be able to use it for tuning.

I may be wrong, but I think it will be a fine performer once everything is tuned in.

Here are a few pics of the final setup.





If someone has some experience with using the Pansat 3500 and the Traxis, and can tell me how the numbers on the meter are similar or different, can you please post your experience?

Now I have to go fight with two rusty bolts. HeHe

Thanks,

Fred

 

[linuxman]

Went up after the last post with a wire brush for my cordless drill and cleaned the bolts as best I could and squirted some PB Blaster on them. I could tell by looking at them, they were never going to come loose.

It started to rain shortly after that, so I went to town and got two new bolts and 8 fender washers figuring that 4 per side would surely be enough to give me what I need.

After it quit raining and it dried out a little, I went back up and sure enough, there was no way the bolts were going to come loose. Pretty much knowing that in advance, I took my dremel with me, and ended up cutting through the lock washers and cutting the bolts off. They were tough nuts to crack, but they finally puked their guts up and surrendered.

After putting two washers per side between the mounting frame and the dish, according to my protractor I gained about one degree of declination. That may be too much, and I may have to take one on each side back out.

It's too late in the day to haul everything back up there to do any more tuning, and we may get a little more rain shortly by watching the radar.

I'll go back up tomorrow right after I get back from Church and see what improvements have been made by the change in declination.

I have my fingers crossed that this will finally change this dish into the performer that I hoped it would be after putting all the work I have into it.

Fred

 

[somery]

That first picture is a good one! Looks like a lot of good equipment standing proud on your roof

 

[linuxman]

Thanks Somery,

That is just the North half. The rest is behind me in that picture.

Fred

 

[linuxman]

I spent about 7 hours on the roof yesterday.

I tried the new declination with the two washers, and it was a little too much. I removed one, and made dozens of other adjustments.

I think I have it pretty much maxed out as far as signal.

The declination gave me about 5% gain across the arc. The readings still seem a bit low according to my readings on the Pansat.

I am satisfied that I have the F/D ratio set about correctly at .40. I have tried it at .42 and .38 and it seems to work best at .40. I have moved the whole feed assembly in and out a total of about half an inch and am currently right at the 44" mark. I had figured the focal length at 44.2"

I am still having a problem with getting anything to come in on AMC6 Ku. It keeps wanting to pull in C-Band channels through the Ku pipeline. I think that is a problem with skew.

I won't be able to do much with it today. I have some other things to do and it is supposed to rain. If I can, I am going to at least pull the Co-Rotor out and bring it in to make sure there aren't any obstructions in it, and replace the servo motor.

Tomorrow I plan to take the Pansat up and hook it up to see what the readings are on it. That is the only way I know how to compare the numbers.

Do any of you have any suggestions?

Should I try to pull the feed-horn in or out dramatically, say an inch or more?

The calulated specs are:

103" Diameter
15" depth
44.2" Focal Length
.43 F/D ratio

I am using Chaparral 20K C-Band and Eagle Aspen .6db LNBs.

Edit:
I did find a second set of calculations that I did early on.
103" Diameter
14-7/8" depth
45.2" Focal Length
.44 F/D ratio
Do you think that might make a dramatic difference?

Thanks,

Fred

 

[Inno]

I would think it would probably make a difference. I've never done any digital with a BUD (yet) but my guess would be that a very small adjustment would make a big difference. There are many adjustments with a BUD therefore many places for error.

Looks good though, you're really spending some time to get it right!

 

[linuxman]

Hey Inno!

Thanks for the suggestion. I will probably wait to make any adjustments until after I have hooked up the Pansat and see where the numbers are with it.

After doing some checking with the Pansat this morning on the BV, I am thinking part of the problem might be with the way the Legacy is controlling the skew, especially with AMC6, and it could be across the board. I only have 5 satellites set up in the Legacy right now and I forgot to add that I added G27 with White Springs at 75% SQ yesterday.

You are so right about there being many places for error on a BUD. With no factory specs to go by, it is even more difficult and adding the complications of an analog receiver controlling movement and polarity/skew it is even tougher.

It is going to take some time, but I'll get it one way or another.

Fred

 

[Inno]

It might be to your benefit to forget about getting all the satellites and concentrate on just one bird. Play with all your settings (specifically the focal point and skew) and get the absolute maximum signal you can on just that one. Then setting up the rest might get easier. Once you find the optimal focal point things should improve. Until then it's probably gonna be hit and miss and the weaker satellites could be difficult. I'm sure you've already thought of this but make sure the feedhorn is absolutely centered. I recall further back in this thread that you were using support arms from another dish.

 

[linuxman]

Play with all your settings (specifically the focal point and skew) and get the absolute maximum signal you can on just that one.

That is the approach I have taken, and have pretty much done that on G11.

Since then I have been trying for Ku on the ends of the arc to make sure I was tracking properly and it appears that I am. I would like to get AMC6 Ku tuned in for the farthest East satellite.

I replaced the servo motor a while ago, and followed the explicit instructions from a member on another forum which I didn't know about.

Connect the replacement servo motor to the wiring, but do not install it to the feedhorn. See that the square peg on the servo motor can turn a full 180 degrees (half a turn) as you or someone else runs the skew setting in the 4DTV all the way from -90, through 0, onto +90 and back several times. Stop with the skew setting in the 0 position to center the replacement servo.

With your fingers, gently turn the probe throughout it's rotation and back several times, to be sure it is able to turn freely with a feather touch. Stop with it in the center of it's travel range, so that it will match the servo when you reinstall. Be sure to use the rubber O-ring to seal against water intrusion.

quote from Mechtech
Well my probe wasn't turning with a feather touch for sure. I fixed it, don't ask how, but if it quits working in a couple of months, I'll know why.

The other thing I noticed was that the Legacy is feeding voltage to the motor even after it has reached it's destination. The Legacy was NIB when I bought it last fall, but had still been sitting on the shelf for over 10 years. So I may have a two-fold problem.

It may have been more mechanical than anything else. I'll know about the SQ strength when I get the Pansat hooked up and I'll know about the polarity/skew when the Pansat controls the skew etc for itself.

I am making arrangements to get a GI 450i from a fellow forum member here to take over for the Legacy. In the meantime, depending on the Pansat results, I might try the TRX-1820 to see if there is a difference.

Fred

 

[Inno]

When you say the Legacy is feeding voltage even after the motor has reached it's destination, do you mean that it keeps moving or tries to keep moving and can't because of a physical limit?
I think maybe one of the limitations of using a BUD is that the polarity servo is a little too rough for Ku band use. It would be nice if there were a more refined motor for skewing in our digital world.

 

[linuxman]

When you say the Legacy is feeding voltage even after the motor has reached it's destination, do you mean that it keeps moving or tries to keep moving and can't because of a physical limit?

It doesn't try to move, and is no where near a physical limit, it just hums for a couple of seconds and then stops humming. I have since tried it out on my old Drake ESR-1524 and it does it on that one too, so I don't think that was a big deal.

I do however think that the hard turning probe was a problem, and that is now fixed.

I think maybe one of the limitations of using a BUD is that the polarity servo is a little too rough for Ku band use.

The servo controller on the Pansat does a more delicate job of moving the skew etc. than the old analog receivers do. Another problem is with the movement of the dish using the analog receivers. The VBox II has a separate remote that will just inch the dish over if you want it to.

I think I found the biggest problem this morning. One of the support arms slipped at the scalar ring, and it was off the center of the dish by about 4 inches. I made the correction and put the feed-horn back in place after changing out the servo motor. I have to leave right now, but will be back in a couple of hours and then I am going up and finish this thing off hopefully.

I am also going to do as you suggested earlier and concentrate on getting the best SQ I can out of G11 Ku with F/D, Focal Length etc and take it from there.

I am also going to hook up the Pansat just to compare numbers.

Will report back later today.

Fred

 

[linuxman]

I think I made some good progress today. I concentrated on getting the most out of my TS satellite. 91W - G11 (G7) in the analog.

I actually improved the Ku there by about 10% over yesterday and the C-Band by 3 or 4. The change was significant enough that I put the second washer back in for a little more declination and it did help G11 by a point or two, but killed White Springs off, the other stronger TPs are still there, but White Springs went away. On the East side, ONN dropped to 60%. So I'll have to take it back out the next time I go up which will probably be Friday now.

I have a .38 F/D ratio now and the Focal Length is 43-5/8". That seems to give the best signal.

I don't know what it is about this dish that is making it so hard to tune in. Everything should be booming off the surface, but it isn't. The C-Band seems to be doing better than the Ku. The Ku LNB is a brand new Eagle Aspen .6db. I suppose it could be a bad LNB. It happens occasionally. I can take it back and exchange it for another one which I might just do.

After I got the best numbers I could adjusting with the Traxis, I hooked up the Pansat just to compare numbers. I left the polarity in the control of the analog box. The C-Band numbers were about the same, but surprisingly enough, the Ku numbers were 20% less on the Pansat than the Traxis. Again, an indicator that the Ku LNB might be bad.

That's all for tonight.

Fred

 

[linuxman]

After thinking this whole scenario over last night, I have come to the conclusion that I need some help.

The original measurements I took on the dish are:
Diameter 103.5" (8' 7-1/2") measured from the center of the curved outside rim
Depth 15"

Which gave a Focal Length of 45.2"
F/D ratio of .44

I measured it at a later point in time:
Diameter 103" (8' 7") from just to the inside of the curved lip
Depth of 14-7/8"

Which gave a Focal Length of 44.2"
F/D ratio of .43

The Co-Rotor only has F/D ratio settings that go to .42 so that was where I started. Am now at .38 as shown above.

This dish should be smoking the meter on the receiver.

I couldn't measure the original Focal Length because one of the support arms had rusted out, and it was just hanging, but if I remember correctly, putting the other two in approximately the center of the dish had the Focal Length at least 6" lower than what I have mine. I don't think the original installer had it right, but then obviously I don't have it right either.

The dish was not warped when setting flat on the ground. I am going to string it again while mounted and run it through the arc just to see if the Feed-horn weight might cause the strings to separate at any position in the arc.

You guys who have been in the business for a long time, I need your help and suggestions. I haven't found the sweet spot yet.

What would you do differently than I have done?

Thanks,

Fred

 

[caddata]

....After thinking this whole scenario over....

Fred:

This idea of "super tweaking" brings up several points.

First, the mathmatical formula which locates the focal point is based on the dish being symmetrical about its centerline. If it's not symmetrical (and it easily could not be) then side to side relocation of the feed is required.

Second, that same formula also assumes the parabolic curve is perfect. If it's less that perfect, the focal point moves in and out.


Third, combine errors in symmetry and curve accuracy and the focal point can be almost anywhere.

And on top of all that, as the reflected signal converges towards the focal point it diverges after it passes it. So, maximum signal allowed into the mouth of the feed is the same for an inch or so either side (in and out) of the true focal point.

Interesting things you're bringing up,
Harold

 

[linuxman]

Thanks Harold,

And on top of all that, as the reflected signal converges towards the focal point it diverges after it passes it. So, maximum signal allowed into the mouth of the feed is the same for an inch or so either side (in and out) of the true focal point.

I knew I could count on you for some direction.

My plan at this point is to find the "inch" of best signal and narrow it down.

Mechanics first! Make sure the dish shows no warpage as it moves through the arc. Use the string test in different places. Remove the second washer I put in yesterday for more declination. I think I have the elevation/declinaton spot found, and the East/West whole assembly pretty well set.

Then move to the farthest point where the sweet spot could be 45.2" with F/D at .42, then slowly bring it closer to the dish moving about 1/4" per adjustment, always making certain the wave-guide and scalar rings are centered and parallel.

I already have a boat load of time in this dish, so what's another week. It will be worth it if I can get the great strong signal I think it will produce.

Thanks again,

Fred

 

[Inno]

Yes you've certainly been putting your time in on this one. I think I for one will benefit from all your expertise when all is said and done. I remember calculating focal length some 16+ years ago for a 6 footer that I had back then. As I recall it was just a rough measurement and it also needed some tweaking. The best way I found then was simply moving it as you have described, a little bit at a time while adjusting nothing else. The tricky part will be adjusting the feedhorn in and out of the scalar ring while not turning it so as not to affect the skew. I guess you could put a mark on the ring and on the tube of the feedhorn.

I had wondered if there were a formula you could use to find the "exact" placement for focal distance and concluded that there were probably too many places where you could have room for error in measuring alone. Caddata confirmed that for me. Being as how the edges of the dish are curved how would you know what point to measure from? Things like that.......and we all know how hard it is to measure round things with any accuracy without at least one extra set of hands.......then you've introduced a whole other point for error if fingers slip etc. when measuring.

At any rate, you can't stop now, you've got some serious time invested! I'm sure the end result will be positive. I took a lot of pride in my little 6 foot dish years ago and all the signals I could pull in with it.......not perfect but I did spend a lot of time tweaking. I still have the dish as a matter of fact but it's been moved 3 or 4 times and isn't exactly true any more. It hasn't been set up for probably 5 years or so, think it's time to do some hunting now that I have the room for it.

 

[linuxman]

Thanks Inno!

Good luck on your dish hunting. I hope you bring home a beauty! Be sure to give us pictures of what you find.

Yes, it will require marking everything, and documenting distance etc. on the way in so if I need to back out to a longer point, I can.

It won't be easy, but nothing good in life ever is.

If you recall, I spent a good bit of time on the Birdview, but that paid off big time. The great part about the BV, is that the calulations were right on the money for it. Course this isn't a Birdview, so that in itself speaks volumes. I still think that with a little patience and time, this one will be worth it too.

Fred

 

[linuxman]

I made some significant progress today. Spent 8 hours on the roof with 20 - 30 Mph winds. I am real close, just too tired to write about it.

BTW, I talked to Gabshere on the phone today. He had a heart attack on Monday. Had two stints put in this week, and will need a couple more. He is doing okay. He just got out of the hospital this afternoon. Keep him in your thoughts and prayers.

More tomorrow.

Fred

 

[linuxman]

I finally finished tuning the F/D ratio and the Focal Length late this afternoon.

The Focal Length is 42-1/8" with a F/D ratio of .040.

The numbers for those interested are:

G27 129W Ku White Springs at 75% SQ
G11 91W TSS CW C-Band is at 76% SQ
G11 91W TSS Ku the three channel test cards are 72% SQ
G17 74W ONN is 82% SQ
AMC6 72W Satops Mux is 75% SQ (finally got them to come in)

All numbers are with the Traxis 3500. I used the Traxis and my Legacy analog for moving the dish and skew to tune this dish in.

The numbers aren't impressive to me, but anything less than Birdview numbers falls short now that I am ruined.

Now that I have that part finished and it doesn't need to be moved any further, I might try the declination/elevation, and total assembly movement again tomorrow after setting up satellites at 135W and 55.5 W. I think I might squeeze out a couple more points.

It has been a long and tedious struggle to find the best F/d ratio and the proper Focal Length. I started at 45-1/4" and worked my way towards the dish a little at a time.

Fred

 

[voomvoom]

Congrarulations on another job done well, from our favorite Dish collector! Keep up the good work Fred!

Al