My SAT-playground

[RimaNTSS]

There are all my 4 antennas on balcony (terrestrial is not visible behind T90). All four connected to separate tuner in GB Quad Plus. Fibos are motorized. I think, this set up will stay at least till spring time. Perhaps I am going to pay little bit more attention to another hobby from now till satisfaction. New hobby, in one or other way is also related to SAT, but not only. And namely this is INOX welding.

 

[archive10]

Nelson_b, thanks for your offer, will not use it this time. Salesman in SAT-shop will give me one to try and take it back if I am not satisfied. With flange I have another difficulty: feedhorh has 6 holes but flange LNB has 8 holes, so I will probably need some kind of adapter between feedhorn and LNB. If I make one than it will still some signal (perhaps).
IMHO: I more and more think that in the system (dish, cable, connectors, diseqcs, LNBs, receiver) more important is dish (size and shape). maybe 85% of system performance belongs to dish, and rest 15% is dispersed between other elements.
View attachment 57307 View attachment 57308

I dawns on me now: Your Prodelin 1.8 meter dishes are type 1183 with an f/D of 0.6, whereas the feedhorn you have is meant for an 0.8 f/D dish. (So are mine)
You should use the feedhorn on the 0.8 f/D dish you purchased some months ago, that should give you better results...
For the 1183s, continue to use universal LNBs - they're generally designed for 0.6 f/D ratios.

 

[RimaNTSS]

St1! I am not really sure about what you are saying about unmatching feedhorn and dish. Previous owner bought those dishes new as a sets from official suppler. Moreover, feedhorn I have gave slightly better reception results than IBU.

 

[archive10]

St1! I am not really sure about what you are saying about unmatching feedhorn and dish. Previous owner bought those dishes new as a sets from official suppler. Moreover, feedhorn I have gave slightly better reception results than IBU.

What I'm saying is:

The feedhorn that you have posted a picture of looks very much like a 39 degree feedhorn, which works with 0.8 f/D dishes. The 50 degree feedhorn which I assume is for 0.6 f/D dishes (and which is the only other Prodelin available for these dishes) looks quite different.

Furthermore, the feedhorn is lying on top a Prodelin model 1194 antenna manual. The 1194 uses 0.8 f/D reflector.

However, you prodelin antennas are model 1183 or 1184 and use reflector type 0179-189 (as in your pics), and they are 0.6 f/D reflectors.

Soooo... if you use the 0.8 f/D feedhorn with the 0.6 f/D dishes, you will in principle not "illuminate" the entire dish, but rather a smaller portion of it (as the feed is closer to the dish than with a 0.8 f/D feed mount should be). You will get, say, effectively a 160 cm dish...

Now, the Prodelin dish you got recently was a type 3180 ka-band dish (which are VERY epensive from new, by the way - list price 7500 USD and up + shipping - I suppose there is pixie dust in the plastic??). General Dynamics list this as an 0.8 f/D dish. In which case putting a standard LNB will "over-illuminate" the dish, i.e. go beyond the rim.

In other words: Use standard LNBs or CM/Gibby feedhorns with the 118x, and the Prodelin feedhorn with the 3180 to get best results...
(and keep the 3180 whatever you do, it should be quite rare if you ever venture into Ka-band reception...)

 

[RimaNTSS]

TBH, I am little bit lost here. Still do not see usefulness of f/d ratio of the offset dish. OK, "d" is probably stands for diameter (horizontal axe). But what is "f"? Distance fro antenna's focal point to where?
Not all producers of converters show f/d. I think that it is much easier to show opening angle of antenna in degrees and as well illumination angle of LNB also in degrees.
For example, from another thread we know that IBU's illumination angle is 84*. And I know for sure that 2 old Prodelins (0179-189) have opening angle of 78*. So, IBU is little bit overiluminating my dish.
How to make antenna's opening angle and LNB's illumination angle match each other? I think there couple of ways to do this matching: find LNB (or feedhorn) with proper illumination angle, and another way - to make "matching device", we spoke about such a device in another thread and thread still not finished.

I need some time to do precise measurements of my last Prodelin, according to what you've said before it should have opening angle about 70*.
I am also bit confused about types of Prodelin feedhorns when one of then is 39* and another one 50*. What those angles mean in practical sense?

 

[beavs2112]

OK, "d" is probably stands for diameter (horizontal axe). But what is "f"? Distance fro antenna's focal point to where? ?

Hi RimaNTSS. I have been following this thread with interest & I think I have an answer to this question. Please refer to Prodelin drawing 4000-031 attached. Prodelin refers to focal length "f" on offset reflectors as the length from the FEEDHORN FOCUS POINT to the start of the curve of the antenna. Not antenna focus point to somewhere.

I am also bit confused about types of Prodelin feedhorns when one of then is 39* and another one 50*. What those angles mean in practical sense?

I think that the 39 or 50 is the angle from centerline of feedthroat to angled side of feed (1/2 of opening angle).

2 x 39 deg = 78 deg. Again it's my theory only. Maybe only Prodelin RF engineers know answer. In practical sense the wider antenna would need a wider angle feed to be properly illuminated.

 

[RimaNTSS]

Prodelin refers to focal length "f" on offset reflectors as the length from the FEEDHORN FOCUS POINT to the start of the curve of the antenna.

Disagree a little, Prodelin refers to distance from FOCAL POINT of the antenna not PHASE CENTER of the feedhorn, but that does not really matter cuz usually those two points located at the same place (when feedhorn properly placed) , only then we can get maximum performance of the SAT-system.

2 x 39 deg = 78 deg.

than could be close to true, however I do not understand why should producer show only half of the angle?! But in case of 50* feedhorn.... I can not imagine antenna with opening angle of 100*! So, I am still puzzled about this.

 

[beavs2112]

It is an interesting topic I think.

Disagree a little, Prodelin refers to distance from FOCAL POINT of the antenna not PHASE CENTER of the feedhorn, but that does not really matter cuz usually those two points located at the same place (when feedhorn properly placed) , only then we can get maximum performance of the SAT-system. .

I agree. I chose the words poorly in a hurry. I knew what I meant in my brain but that doesn't always translate perfectly to my keyboard

I do not understand why should producer show only half of the angle?! But in case of 50* feedhorn.... I can not imagine antenna with opening angle of 100*! So, I am still puzzled about this.

Ok. Maybe my theory isn't correct I wish I knew someone @ GD Satcom (or elsewhere) that has the answer to this question.

 

[RimaNTSS]

As I have 2 types of 1,8m Prodelin antennas, decided to measure last one I got and compare it's parameters to one I have from more than a year ago. I suspect those are antenna series 1183 (Ku band) and 3180 (Ka band).
There is quiet difference between them. Last one is 14mm wider, and other parameters are different too.
string test showed that there is no warpage issues at all.

 

[RimaNTSS]

Finally started to do some TIG welding. Have equipment but conditions to do welding are more than terrible. This is my first welded INOX construction (6mm bolt+washer)
Hope to gain some experience in that domain.

 

[archive10]

string test showed that there is no warpage issues at all.
View attachment 70550

Shouldn't hope so, uness they had been subjected to a fire or similar that could have softened the plastic enough to deform.
Polyester is pretty tough, and dimensionally stable up to the deterioration point. And that's why they're so good for pro-installs; they keep delivering year after year.
(But on the flip side; if you ever put one in a land-fill, it would endure for probably hundreds - if not thousands - of years. Not an e-Dish!)

 

[RimaNTSS]

I in doubts about antenna I have: I do not think it is Prodelin 3180 Series.
There is one old thread in forum, where in post #20 Thomas posted Prodelin 3180 data sheet. I see that dish has same strength ribs at the back, and 4 holes for mounting bolts. But face of the dish has different dimensions....
As I measured yesterday 1800 x 2015 mm, but Prodelin 3180 (after converting inches to mm) has 1810 x 1896 mm.
Also mount my dish has is different from what I saw anywhere else. Moreover, I did not hear Prodelin made dishes with F/D ratio 0.5
So, I am puzzled about made of dish, but still happy I have it, cuz it seems nice one.

 

[RimaNTSS]

Black home for couple of days, 1,8m Prodelin still in same condition I left it 4 month ago. No feedarms, no LNB, ... Nothing

 

[archive10]

Black home for couple of days, 1,8m Prodelin still in same condition I left it 4 month ago. No feedarms, no LNB, ... Nothing View attachment 71117

yes - it looks almost, well, naked! Without purpose in life! such a tragedy! B-)
But I'm sure it wont be long before it sprouts motorized feed-arms with built-in G-point alignment, illumniation check by laster, and auto-skew mechanisms - after all, there's almost a fortnight before normal working weeks resume... 8-}

 

[RimaNTSS]

I was probably not so bad in 2014 if Santa brought me those 3 cards
Now, I think, I will need new PC to accommodate all of them with those different kind of slots. Or, I would better not insert all of them at once?

 

[bonou2]

take a look here :
pc with four cards
all of them working with xp 32byte

thx to @skystar

 

[RimaNTSS]

I had my friend over for X-Mas, so we spent time not only partying but also assembled 32 Bit desktop, running Windows 7. All SAT cards are inserted. Processor is 3 GHz, with 3 GB RAM. 2 hard drives, DVD reader and DVD writer. My initial idea was to buy completely new PC, but now I see I can survive with this "Frankenstein" for some time. Already scanned several satellites on SkyStar HD card and able to watch FTA channels. Could not find drivers for SS1 card yet. That is quiet new experience for me in SAT field.

 

[Captain Jack]

I still don't like scanning with a sat card - somehow doesn't feel natural but it's certainly very useful scanning weak signals and seeing spectrum results.

 

[RimaNTSS]

I've found Echostar dish (that was announced by previous owner), that was also wall-stand and black handle (as I found out black handle was actuator!). Owner was selling cuz he could not install dish on hes new house.
So, I went to pick up stuff and was surprised little bit.... that was not Echostar but.... you know that pattern ;) I did not mind at all Mirror is in ship shape and "Black handle" as well. As a bonus I got polar-mount and galvanized wall-mount. Will not tell how much did I pay for this set to not make anybody jealous.
But, to not make me too happy, there is something missing - 4 screws to connect dish to polar-mount! But, maybe that is good, anyway, I would change them to INOX made. Can anybody tell me proper size of those screws? I think something like 8mm and approximately 70-80mm.

 

[Riverblue]

That looks like a Channel Master to me, I've got the specs for the dish/screws. I'll dig it out for you Rima