Fibo 1.2m v Channel master 1.2m

[Riverblue]

Slightly off topic, here's some links that helped me get my head around the calcs in post 14, and provided an in depth insight into the technical aspects of our hobby, if anyone is interested
/https://www.labvolt.com/downloads/87768_F0.pdf

/http://www.ieee.li/pdf/viewgraphs/fundamentals_satellite_communication_part_2.pdf

/Antennas for Satellite Communications

/Satellite antennas - ABC Guides

There is a lot to read though! But it is a lot clearer now

 

[Riverblue]

From what I can see given two dishes of the same size, one an offset type the other gregorian, both at the same location and in perfect condition, with lnbs of the same performance and set up correctly with the right equipment, then the gregorian should provide slightly better results. But I can't see any factual information to back up claims that a gregorian dish will equal or outperform an equally well set up quality offset dish of a substantially larger size, which was the claim (by another) that lead to my discussion initially and seems (to me) to be somewhat of an urban myth not backed up by fact IMHO. But I'm happy to be proved wrong because I am by no means an "expert"

 

[Captain Jack]

Here's my experience: http://www.satellites.co.uk/forums/threads/project-fibo.155379/page-7#post-811789

 

[BlindFaith]

From what I can see given two dishes of the same size, one an offset type the other gregorian

It's not offset vs. gregorian. It's single reflector vs. double reflector. Fibo is offset as well ;)

the real advantage is that the secondary reflector may be used to reshape the illumination of the reflector for better performance.

http://www.w1ghz.org/antbook/conf/Multiple_reflector_antennas.pdf

 

[Riverblue]

It's not offset vs. gregorian. It's single reflector vs. double reflector. Fibo is offset as well ;)



http://www.w1ghz.org/antbook/conf/Multiple_reflector_antennas.pdf

You just want to make my head hurt again don't you?

 

[BlindFaith]

nope, but read this again

the real advantage is that the secondary reflector may be used to reshape the illumination of the reflector for better performance.

 

[Riverblue]

nope, but read this again

Yep, read it, again!;) Okay, offset v offset gregorian, but you knew what I meant, we are just quibbling over semantics.

I still refer to my post #22, I agreed that the "offset gregorian" should perform better than a similar sized/installed/quality "offset" dish.

But, I have still to see or read anything to back up this "urban myth" that a "gregorian offset" performs way beyond it's size! In post #16 CJ states that the Fibo was slightly better than the Channel Master but was "walked all over by his 1.5m Gibby", that suggests to me that it's performance wasn't even close! That hardly backs up the statement that "my Fibo performs like a 1.8m dish" by "another" Maybe a poorly installed one.

 

[BlindFaith]

My 120cm Echostar is in fact a channel master. It's in place since more than 20 years and survived a couple of storms. The arkivator actuator (optocoupler) is still working very precisely. Only the LNB(F) has been replaced. The 1st was an expensive Chaparral wideband lnb ;) The mount was controlled by an Echostar SR8700 positioner that was replaced after the power unit failed by a LT8700 with RS232 interface. No USALS or similar crap ;)

I don't think that a FIBO type would have lasted that long

 

[Riverblue]

My 120cm Echostar is in fact a channel master. It's in place since more than 20 years and survived a couple of storms.

I don't think that a FIBO type would have lasted that long

That's what I like about Channel Masters (and the like), they are bloody solid and nigh on unbreakable and they do the job!

 

[Captain Jack]

Yes I am not sure what I prefer. The tough CM or the not as thought but slightly better performing/looking Fibo.

No, I do know. The 1.8m CM

 

[Riverblue]

Yes I am not sure what I prefer. The tough CM or the not as thought but slightly better performing/looking Fibo.

No, I do know. The 1.8m CM

If only . . . maybe if I . . . . . . No stop . . . . NO MORE

 

[RimaNTSS]

No, I do know. The 1.8m CM

Perhaps CM in Gregory design would be even better.

 

[Riverblue]

Perhaps CM in Gregory design would be even better.

What, like this
http://www.skywareglobal.com/images/pdf/Prod.sheets 2012/Type_244_Dual_Optics_VST018.pdf
Enjoy

 

[AndyX]

My 120cm Echostar is in fact a channel master. It's in place since more than 20 years and survived a couple of storms. The arkivator actuator (optocoupler) is still working very precisely. Only the LNB(F) has been replaced. The 1st was an expensive Chaparral wideband lnb ;) The mount was controlled by an Echostar SR8700 positioner that was replaced after the power unit failed by a LT8700 with RS232 interface. No USALS or similar crap ;)

I don't think that a FIBO type would have lasted that long

You are right. My Fibo hasn't lasted 20 years... but close at 19 years, although the dish face itself was replaced within 1st year after some vandals decided to throw rocks at it. There is now a fence around the garden and it is safer now our neighbour dumped her "boyfriend"!

 

[Riverblue]

You are right. My Fibo hasn't lasted 20 years... but close at 19 years, although the dish face itself was replaced within 1st year after some vandals decided to throw rocks at it. There is now a fence around the garden and it is safer now our neighbour dumped her "boyfriend"!

Wow, 19 years, that's good going, sounds pretty robust to me. Is it still on the original motor, assuming it's motorised.

 

[RimaNTSS]

What, like this
http://www.skywareglobal.com/images/pdf/Prod.sheets 2012/Type_244_Dual_Optics_VST018.pdf

Yep, but only 1,8m. However, 2,4m is even better

 

[AndyX]

Wow, 19 years, that's good going, sounds pretty robust to me. Is it still on the original motor, assuming it's motorised.

The original motor used an optic sensor with a 5 volt supply. I swapped it for a reed guided modified original motor when the optic sensor failed. The dish had replaced a channel master 1.2m when I wanted to have a higher gain dish without the impact and expense of a larger dish.

 

[Trust]

@Trust1, IMHO it's not that easy to compare the dishes. A gregorian dish normally comes with a matched feedhorn which could give an additional advantage compared to a standard offset-LNBF.

The Fibo has still his original feedhorn , to it a modded BU single at the time of that test .
@ Rimants , believe me , my 120 is not warped , the extra rods at the back keeps it in shape .

 

[RimaNTSS]

@ Rimants , believe me , my 120 is not warped , the extra rods at the back keeps it in shape .

@Trust1 that is why I've said

it is not so easy to find Fibo in ideal shape

That means it is still possible to find not warped dishes
I doubt you did not checked and corrected shape of your antenna (antennas). Dishes I checked for warpage (especially 90cm) all out of ideal shape. And, THB, I am afraid to string my Fibo120.:mad:

 

[Riverblue]

The original motor used an optic sensor with a 5 volt supply. I swapped it for a reed guided modified original motor when the optic sensor failed. The dish had replaced a channel master 1.2m when I wanted to have a higher gain dish without the impact and expense of a larger dish.

So you've had both dishes, can you dispel/back up the "urban myth" about the phenomenal performance of the Fibo, in your experience did the Fibo massively outperform the Channel Master (assuming it was a 1.2m!) or were the differences a lot smaller?