Focal Length on 8ft mesh - no signal

[pookah]

Maybe someone can shed some light on what's wrong here. Got my 8ft from tek2000. Took me 2 days to put that LEGO dish together and all seemed well until I got to the part where I had to install feedhorn rods. The rods are 34" long and the FL (as per documentation) should be 36" but mine sits at 28". Spent whole day trying to get any signal in KU or C bands with no luck. I got a Norsat LNB and one of those cheap C/KU combo lnbs. Perhaps someone has the same dish and would be able to confirm the FL?

Any hints would be appreciated.


Few pics

https://postimg.org/image/4p6q83cph/

https://postimg.org/image/5fzgdvf2t/

https://postimg.org/image/gguliw7bp/

Thanks

 

[Titanium]

This LNBF install guide might help. The FD ratio setting and the FL measurement calculation information is at the bottom of page one. http://titaniumsatellite.com/downloads/Guides/LNBF Install Guide.pdf

The FD ratio is not measured in inches. FD ratio is the setting of the feedhorn within the scalar using the FD ratio marks stamped on the side of the feedhorn (if adjustable, but your feedhorn appears to be a fixed FD type). The FL measurement is the distance from the center of the reflector surface to 1/4" inside the feedhorn opening (throat).

I initially would only be aiming at a C-band satellite. KU reception on that size dish will be more challenging and should only attemp once the dish is receiving C-band.

Please provide your location and we can advise on which satellite and a strong transponder near the top of the arc.

If you will be installing the polarity servo motor, the feedhorn/scalar should be installed with the vertical axis aligned up with 12/6 o'clock position with the dish positioned at the top of the arc. from the photo, it looks to be installed at 9/3 o'clock which would make the polarity setting 90 degrees out or rotation.

 

[panth1]

I have one. Rod lengths are 47". If yours are only 34" then they sent you the wrong ones.

 

[pookah]

This LNBF install guide might help. The FD ratio setting and the FL measurement calculation information is at the bottom of page one. http://titaniumsatellite.com/downloads/Guides/LNBF Install Guide.pdf

The FD ratio is not measured in inches. FD ratio is the setting of the feedhorn within the scalar using the FD ratio marks stamped on the side of the feedhorn (if adjustable, but your feedhorn appears to be a fixed FD type). The FL measurement is the distance from the center of the reflector surface to 1/4" inside the feedhorn opening (throat).

I initially would only be aiming at a C-band satellite. KU reception on that size dish will be more challenging and should only attemp once the dish is receiving C-band.

Please provide your location and we can advise on which satellite and a strong transponder near the top of the arc.

If you will be installing the polarity servo motor, the feedhorn/scalar should be installed with the vertical axis aligned up with 12/6 o'clock position with the dish positioned at the top of the arc. from the photo, it looks to be installed at 9/3 o'clock which would make the polarity setting 90 degrees out or rotation.

Thank you! I will make the adjustments and see how it goes.

I have one. Rod lengths are 47". If yours are only 34" then they sent you the wrong ones.

Mine are much shorter however, the rods you have probably mount to the edge/rim of the dish? Mine are much shorter but mount directly on the pellet about 1/3 from the outside rim. I just checked tek2000 website and it says FL is 28.5" but rod size is at 40" in their tech specs - which makes little sense to me.

 

[FTA4PA]

Mine are much shorter however, the rods you have probably mount to the edge/rim of the dish? Mine are much shorter but mount directly on the pellet about 1/3 from the outside rim.

I have an 8' Tek2000 dish and it was one of the early ones. Yes, the original rods were 47" (49" including hole/mount on each end) and fastened to the outer edge of the rim. Apparently these dishes have undergone some design changes over the years. I know that the 12' now has the rods mount to the surface of the reflector instead of the edge so it is likely that the 8' does now as well so they would be shorter.

 

[pookah]

I would like to THANK everyone for their contribution. I followed Titanium's suggestion about the positioning of the scalar ring and BINGO. This is my first BUD and I must admit that these dishes are not very well built; poor welding job on the inside of the saddle making it difficult to fine tune horizontal position, mesh is poorly placed on the frame etc) but after spending few hours I finally got a lock on Galaxy 19 and then Galaxy17.

 

[panth1]

Mine are much shorter however, the rods you have probably mount to the edge/rim of the dish? Mine are much shorter but mount directly on the pellet about 1/3 from the outside rim. I just checked tek2000 website and it says FL is 28.5" but rod size is at 40" in their tech specs - which makes little sense to me.

The dish I have matches the tech specs currently on their web site. Rod length: 47". Rod mount: 5.5" from rim on panel face. Looking at your pictures in more detail, they moved the mounts even further in now so the shorter rods would make sense.