Channel master frankensteined

RimaNTSS

RimaNTSS

Super Moderator
Staff member
My Satellite Setup
Some SAT-related hardware.
My Location
N-E from Riga
Hi! Under the influence of another thread I have decided to play little bit more with CM 1.2m antenna, namely to convert it to double-reflector design. All I need is to make set of parts (mostly INOX) which will allow to nicely install Fibo bottom feedarm with the subreflector and feedhorn, or even without Fibo feedhorn to play with standard Ku or C band LNBFs. Feedarm, subreflector and feedhorn from 1.2m Fibo or 90cm Fibo can be used here. Actually, set is almost ready, only sidearms are missing (need to buy some INOX 10mm tubes). At the end of the day I will have 2x CM 1.2m installed shoulder to shoulder, one in usual setup and another one in double-reflector mode and then see which performs better. By theory dual-reflector antenna systems should bring ~10% better performance, side-lobes and X-pol minimized.
 

Attachments

  • IMG_20190530_114321 (Large).webp
    IMG_20190530_114321 (Large).webp
    116.9 KB · Views: 253
  • IMG_20190530_114335 (Large).webp
    IMG_20190530_114335 (Large).webp
    284.4 KB · Views: 260
  • IMG_20190530_114340 (Large).webp
    IMG_20190530_114340 (Large).webp
    545.8 KB · Views: 246
  • IMG_20190530_114424 (Large).webp
    IMG_20190530_114424 (Large).webp
    518.9 KB · Views: 232
  • IMG_20190530_120214 (Large).webp
    IMG_20190530_120214 (Large).webp
    401.7 KB · Views: 250
Also done the feedarms. It is not so easy to find the proper position of the sub.... first I need to tune antenna to some satellite in the normal setup (just main mirror and LNBF in focus). Then, without moving the main mirror, sub should be installed and manually find it's proper position by maximum signal. I've done this procedure several times.... yes, it takes time :confused, but that is fun! :Y
 

Attachments

  • IMG_20190530_152738 (Large).webp
    IMG_20190530_152738 (Large).webp
    309.7 KB · Views: 213
  • IMG_20190530_152819 (Large).webp
    IMG_20190530_152819 (Large).webp
    456.6 KB · Views: 203
  • IMG_20190530_173159 (Large).webp
    IMG_20190530_173159 (Large).webp
    383.2 KB · Views: 193
  • IMG_20190530_173847 (Large).webp
    IMG_20190530_173847 (Large).webp
    141.4 KB · Views: 185
  • IMG_20190530_173856 (Large).webp
    IMG_20190530_173856 (Large).webp
    70.7 KB · Views: 201
You are very skilled indeed
 
Thanks all!
Captain Jack said:
Any chance of making this for the 1.8m?
Click to expand...
The only difference here is the length of feedarms. And, because of the different length the diameter of tubes should be different as well. For 1.2m antenna 10-12mm tubes for side-feedarms , but for 1.8m antennas 14mm tubes are better be used. I will probably do the set for 1.8m CM dish soon to see how it works.
 
Well, there is some difference between 1.2m and 1.8m dishes.... and not only sizes of the mirrors. For 1.8m dish it is more appropriate to use M8 bolts & nuts , but for 1.2m dish M6 is more than enough. Of course, feedarms are in different length and different diameter tubes are used (12mm for 1.2m and 14mm for 1.8m). Other-ways nothing more differs and it is only matter of tuning, adjusting and tests.
 

Attachments

  • IMG_20190616_200013 (Large).webp
    IMG_20190616_200013 (Large).webp
    154.8 KB · Views: 173
  • IMG_20190617_211818 (Large).webp
    IMG_20190617_211818 (Large).webp
    308.4 KB · Views: 188
  • IMG_20190617_211826 (Large).webp
    IMG_20190617_211826 (Large).webp
    272.9 KB · Views: 178
  • IMG_20190617_211833 (Large).webp
    IMG_20190617_211833 (Large).webp
    478 KB · Views: 154
  • IMG_20190617_222708 (Large).webp
    IMG_20190617_222708 (Large).webp
    124.5 KB · Views: 162
Alex!
Theoretically, Gregorian and Cassagrain design of antenna system performs ~10% better than single reflector system. When I was experimenting with double-reflector systems I felt that performance was a little better (not worse for sure) than same antenna without sub. Another point is it is fun doing such experiments. We are talking about hobby, do not we? :D .
 
@RimaNTSS - good to hear from you again (not much lately!) :D

How's the health situation in your neck of the "woods"?
 
Hi, All!

As I have found out that several forum members are interested in transforming their offset antennas to double-reflector ones. I fully support this wiliness, as I personally see real potential in this transformation. I have gone this way, and I am pretty satisfied by the process itself and also by the performance of dual-reflector systems. The main question by users was about how to do this transformation? I have an answer…. In 2 parts. Part Nr.1 – theoretical. Part Nr.2- practical. Should we discuss those parts one by one?
 
RimaNTSS said:
Hi, All!

As I have found out that several forum members are interested in transforming their offset antennas to double-reflector ones. I fully support this wiliness, as I personally see real potential in this transformation. I have gone this way, and I am pretty satisfied by the process itself and also by the performance of dual-reflector systems. The main question by users was about how to do this transformation? I have an answer…. In 2 parts. Part Nr.1 – theoretical. Part Nr.2- practical. Should we discuss those parts one by one?
Click to expand...
Wok do you suggest first ?
 
RimaNTSS said:
Well, there is some difference between 1.2m and 1.8m dishes.... and not only sizes of the mirrors. For 1.8m dish it is more appropriate to use M8 bolts & nuts , but for 1.2m dish M6 is more than enough. Of course, feedarms are in different length and different diameter tubes are used (12mm for 1.2m and 14mm for 1.8m). Other-ways nothing more differs and it is only matter of tuning, adjusting and tests.
Click to expand...
Opening this old thread..This is on my 'to have a go' list now...Have you saved any measurements, angles etc for the 1.8m Rima?
 
RimaNTSS said:
Hi, All!

As I have found out that several forum members are interested in transforming their offset antennas to double-reflector ones. I fully support this wiliness, as I personally see real potential in this transformation. I have gone this way, and I am pretty satisfied by the process itself and also by the performance of dual-reflector systems. The main question by users was about how to do this transformation? I have an answer…. In 2 parts. Part Nr.1 – theoretical. Part Nr.2- practical. Should we discuss those parts one by one?
Click to expand...
You know..... I still have the parts you sent me in 2019 to put this together and with everything going on, I never got around to it! I have a lot of plans on my list for CM and this will be one of them.
 
I was exploring possibilities for making the SUBs, but came in to the conclusion this makes no sense. So, the best way, IMHO, is to use factory made SUBs, feedarms and feedhorns from Fibo antennas.
 
RimaNTSS said:
I was exploring possibilities for making the SUBs, but came in to the conclusion this makes no sense. So, the best way, IMHO, is to use factory made SUBs, feedarms and feedhorns from Fibo antennas.
Click to expand...
I see INOX bits have been added to the 1.8 design, I take it these can still be made by yourself?
 
Back
Top