Feedhorn ident

[archive10]

If this is drawing and not just picture than opening angle of this antenna is about 70*.
View attachment 69858
I do not think so. Perhaps here we coming again to the issue "Where is phase center of feedhorn?"

Could be. Maybe also some physical angle, which is different from the operating angle. Dunno.,

 

[RimaNTSS]

For example: Red-56* can be feedhorn opening angle (can be easily measured) , but Green 85* can be feedhorn illumination angle (can only be calculated in some way).

 

[solly]

any solotion of prime focus it only for offset

 

[Channel Hopper]

any solotion of prime focus it only for offset

The feeds that have been bought at auction are only for offset antennas, Prodelin do (or did last time I looked) have a Ku approved feed system for their prime focus antennas.

 

[solly]

it have f/d 033 prodlin prime focus ?

 

[Channel Hopper]

None of the Prodelin antennas have f/d of 0.33

The 2.4m system is 0.37 f/d ratio.

The 3 metre dish has an f/d of 0.3, 3.4m (o.36) and 3.7m (0.37 or 0.375, depending on the manual supplied)

Their 4.5 metre dish is a beauty if assembled correctly (BT engineers at Madley know all about screwing up their purchase from me in 2002) with a similar f/d to that of the 3.7m reflector, though the additional panels do change the reflector characteristics, depending on the feed used.

http://www.gdsatcom.com/vsat/Technical_Docs/geometry_drawings/4000-021.pdf

 

[archive10]

Measurements of the two feed designs

Model 0800-1375 39 deg . Outside diameter of the feed is 14.6 cm (5.76 inches). Feed opening diameter 12.75 cm. Length 10.9 cm. Intended for use with f/d=0.8 ETSI antenna approval

Model 0800-309 - 51 degree feed. Outside diameter 13.3 cm.(5.23 inches). Feed opening diameter 11.2cm. Length 9.1 cm. Intended for f/d=0.6 antennas such as 1123, 1124, 1125, 1183, 1184, 1251, 1255, 1381, 1383.

There is also a 50 degree antenna feed for older design antennas. 0800-1290 but I doubt you have this version.

Got the feeds this afternoon.
They are spot on for the figures you mention for a 39 degree feed horn.
They have the same number of rings, and looks generally very similar.
There are, however no markings of any kind on the metal. So no definite confirmation of the origin.
Each have a clear (thin) plastic membrane over the opening, and a blue plastic seal over the flange end. This is marked with "impregnated", whatever that implies.
So I would conclude that they are quite likely Prodelin Model 0800-1375. Or very good copies (unlikely).

 

[beavs2112]

This thread has some very interesting information in it

 

[archive10]

Digesting the fact that these were most likely Prodelin 0.8 f/D feeds, I realised that I could probably not use them with practical benefits on any of my dishes.
Isn't it almost uncanny then, that I, two weeks later, should stumble across a 0.8 f/D Prodelin dish at a really low price only 20 km away from me... and without a feedhorn??

Nevertheless, I need some sort of flange adapter to mate the feedhorn with an C120 LNB. Probably a round one - I suspect it just needs to carry the signal a bit further, although have not yet measured the bore of the feed compared to the bore of a C120.
Maybe it's just a matter of drilling a couple of new holes in the feedhorn to match, say, three or four of the holes in a C120.
But that leaves little room for fine-adjusting the distance of the LNB compared to the dish...

I'ts not urgent, but at least I can start thinking about this over the winter, and do some experiments.
What do you guys think?

 

[archive10]

Nevertheless, I need some sort of flange adapter to mate the feedhorn with an C120 LNB. Probably a round one - I suspect it just needs to carry the signal a bit further, although have not yet measured the bore of the feed compared to the bore of a C120.

May something like this? (I think it comes with the 0183-725).

 

[RimaNTSS]

I ordered adapted LNB as here in post 307, reception results were good enough.

 

[archive10]

I ordered adapted LNB as here in post 307, reception results were good enough.

Did you machine off the original feedhorn, and make a custom new 6-hole flange for it?

 

[RimaNTSS]

No, this part, which is glued to LNB is machined in the way it fits feedhorn.

 

[RimaNTSS]

I did not want to buy fabricated adapter.... too expensive.

 

[samoloko]

st1 did you receive feedhorns - did you test them on your channel master 1.2 or 1.8
what are their Illumination angle
what Is Illumination angle of Skyware feed which can be found on channel master 1.2 and 1.8 Ku band dishes

 

[archive10]

st1 did you receive feedhorns - did you test them on your channel master 1.2 or 1.8
what are their Illumination angle
what Is Illumination angle of Skyware feed which can be found on channel master 1.2 and 1.8 Ku band dishes

1) Yes
2) No
3) Don't know. But they're most definitely Prodelin "39 degree" feed-horns, meant for 0.8 f/D dishes.
4) Don't know. But the Skyware Global feeds mostly seen on ebay/this forum are for the 0.6 f/D ku band dishes.

 

[stephenG]

1) Yes
2) No
3) Don't know. But they're most definitely Prodelin "39 degree" feed-horns, meant for 0.8 f/D dishes.
4) Don't know. But the Skyware Global feeds mostly seen on ebay/this forum are for the 0.6 f/D ku band dishes.

Did you try the feedhorns ?.

 

[stephenG]

Model 0800-309 - 51 degree feed. Outside diameter 13.3 cm.(5.23 inches). Feed opening diameter 11.2cm. Length 9.1 cm. Intended for f/d=0.6 antennas such as 1123, 1124, 1125, 1183, 1184, 1251, 1255, 1381, 1383.

I have a Gibertini 1,5m offset dish with with f/d=0.66. There is a Model 0800-309 feedhorn on ebay, and I am wondering if I might get better results than with the Gibertini feedhorn (which isn't that much better than a good universal LN.

Do you know if the flange is C120 or something else ?, and how it might be adapted to C120.

Thanks

 

[archive10]

Did you try the feedhorns ?.

Nope.
They are most definitely 0.8 f/D feedhorns (long focal depth), so not suitable for 0.6 f/D dishes (as all my Channel Masters dishes are).
Using those feedhorns would under-illuminate the dish (shallower opening angle), no point in trying.
Will spare those for the Prodelin 1241, which is a 0.8 f/D dish.
I have Channel Master 0.6 feedhorns instead to try on the CM dishes.
(looking forward to summer vacation!)

 

[archive10]

I have a Gibertini 1,5m offset dish with with f/d=0.66. There is a Model 0800-309 feedhorn on ebay, and I am wondering if I might get better results than with the Gibertini feedhorn (which isn't that much better than a good universal LN.

Do you know if the flange is C120 or something else ?, and how it might be adapted to C120.

Thanks

The 0800-309 may or may not give you slightly better results than the Gib feedhorn - impossible to say without trying.
But the flange is a non-standard Prodelin with six holes (no thread), so you need an adapter, or get handy (and precise) with an superglue, or even a drill...