got a weird issue on my 1.2m - advice pls

[Manikm909]

hey guys,

as you know last week i setup my new laminas 1.2 - i set it up quickly as the weather was bad....but i was tracking the arc, and knew i needed to fine tune

today was fine tune day.

i got some interesting results....so, 1w is my setup sat - so made sure i was gettin 92% signal on that.

then i checked extreme ends of arc, so i checked, and i could go from 34.5w to 52e - both ends 98% on most TPs - HOWEVER, on the 13e and 19e im getting lower than expected signals...like 65% 70% on RAI and RTL respectively.

i checked nothing was blocking, so i tried manually seeing what i could get on 19e, and manually it went up to 89% -91%....

i dont get how i can get strong signal in middle, and both ends of ARC but what should be strong signals aren't so much....could it be the LNB? im using a Inverto Black Ultra - any known issues with that LNB???

thanks all!

 

[a33]

Just some thoughts:

Is the mast still plumb, in any position of the dish? Or might the weight of the dish pull the mast out of plumbness?

Is the asymmetrical tightening of the motor clamps on the mast causing distorted, non-plumb position of the motor bracket?
(see 3rd photo in your post here: Going from 1m gibertini to 1.2 laminas - worth the cost \ hassle?? )

Don't know if these would cause the symptoms you have, though. Just some premature thoughts of mine.

Greetz,
A33

 

[Manikm909]

thank you very much.

You could be right - i will losen everything tomorrow - i just hate wasting time doing this alignment stuff. Spent 3 hours today....

the dish bracket however is a pleasure to work with, unlike the old Triax TD110

 

[jeallen01]

Might suspect that the declination setting is a "very little bit off" - either a little too high or low??

 

[a33]

Might suspect that the declination setting is a "very little bit off" - either a little too high or low??

I wondered about that too.
But if he has optimal reception at 34.5w and 52e, AND at the center of the arc (where he presumably started his alignment), that would not give this symptoms, I think?

BTW @manikm909 : did you use the so-called modified motor angles?
For latitude 51.5N (somewhere in Kent), motor elevation angle would be about 37.8 degrees, and dish declination offset angle would be about 6.8 degrees.
That way you follow the arc better, than with the 'traditional' motor angles. So less fine-adjustment would be necessary!

(I have a motorized Triax TD115. I know what you mean...!)

Greetz,
A33

 

[ozumo]

Are your signal percentages for signal strength or quality?

Pre-skew on Astra may explain some of the signal gain of the fixed setup. Or are you just nudging/pulling on the dish while still on the motor to recover the signal? If so In which direction does the signal improve (up/down, east/west)?

If the LNB was overloading the tuner then I'd expect issues on 28.2e also.

 

[jeallen01]

Might suspect that the declination setting is a "very little bit off" - either a little too high or low??

OTOH, I might now also suspect that the "0 degrees" is a "very little bit" off because 34.5W and 52E signals are very strong in the UK, and those strong signals on those sats might not be a good indication of correct azimuth alignment - and then, maybe, the LNB may not be absolutely vertical, as it must be on a motorised dish.

Others may, however, have differing views on the above.

 

[Channel Hopper]

I'm inclined (sic) to the view that ther is some play in the motor gearbox, which has been amplified by the larger dish, both weight and narrower beamwidth.

 

[Manikm909]

to be honest guys, i NEVER use suggested angles - EXCEPT for motor - i'm at 51 latitude - so i set the motor bracket angle to this, i make sure motor is set to zero, then i move the motor and dish until i find 1w - i then lock up motor, and then by adjusting dish only, use Al Jazeera to align \ tweak max signal - then i tighten up and see how it goes east to west.

today i spent 3 hours, each time slightly moving motor elevation slightly above 51, about 3 degrees either side (incrementally), no matter what i tried, i could always get pretty good signals on 30w and 45e - and of course on 1w - but 13e and 19e, just arent maxxing, theyre not crap dont get me wrong, but there not maxxed out...phoenix hd channel on 19e for example should be about 89% but im getting 70% when driving dish there from 1w

at one point, as a test, i thought WHAT can i actually receive on 19e - Phoenix HD - so i drove dish to 19e, then i got up ladder, and moved DISH up \ down only - to peak, and got 89% (from 70%)

i then went back to 1w, tried tweaking motor elevation again, maxed signal on Al Jazeera, and off i went again, no matter what i tried, i could never bring in 19e or 13e on strong signals, average at best.

i will try again tomorrow, with a fresh mindset and rested body.

i think i will slacken off motor, and make the motor brackets parallel to each other as a start- my pole i plumb, however, i do notice, that tightening the motor brackets can affect signal - i take this into account and this might be the problem, the dark motor brackets are quite soft compared to TM2600 and they bend if you overtighten

 

[jeallen01]

.., the dark motor brackets are quite soft compared to TM2600 and they bend if you overtighten

Yup, they are "quite soft" - so, be careful how you tighten the nuts, but then "look out" for further softening over time (happened with the one on which the 1.2 gibby is mounted) resulting in the dish elevation changing downwards, but I think that that may well have continued in spite of my mods to the clamps to prevent it.

 

[Manikm909]

im gonna try another LNB today and play with the skew, but im not hopeful. my other thought is maybe the dish isnt 100% clamped onto motor mount correctly, but then surely id see issues either end of ARC

 

[sonnetpete]

Before you alter anything mechanical, how about altering the sat position (i.e. 19.2 to 19.3 or 19.1) and see if that makes a difference.

 

[Channel Hopper]

i think i will slacken off motor, and make the motor brackets parallel to each other as a start- my pole i plumb, however, i do notice, that tightening the motor brackets can affect signal - i take this into account and this might be the problem, the dark motor brackets are quite soft compared to TM2600 and they bend if you overtighten

You should be able to swop out the Dark Motor brackets for the old TM ones, though as sonnetpete says, try off the pole mods first. There is an adjustable backlash on the motor, just behind one of the pivot bolts on the locking plate after that.

 

[Manikm909]

guess what guys!

IT WAS THE LNB at fault - replaced it with a TM Gold - and straight away got 89% signal on Phoenix HD19e and higher on other channels - now getting high 90's all through ARC (where known possible)

 

[Lazarus]

guess what guys!

IT WAS THE LNB at fault - replaced it with a TM Gold - and straight away got 89% signal on Phoenix HD19e and higher on other channels - now getting high 90's all through ARC (where known possible)

Bravo.

Always have a spare LNB available!

 

[Manikm909]

yes, it makes sense now that i come to think of it, logically the arc seemed spot on - it had to be the LNB - the least hassle to sort out too (apart from the awkward LNB holder on the Laminas (2 screws with a nut)) - i loved the hinged system on the Gibertini.

 

[jeallen01]

Bravo.

Always have a spare LNB available!

Or 2 or 3 or 4 or......

 

[Manikm909]

yes, and if i hadnt had a spare one, i'd potentially be thnking and possibly regretting buying a bigger dish

 

[Captain Jack]

It's more likely to be an issue with LNB giving too much gain to the receiver and it not being able to compensate, rather than the LNB being faulty. I had to the same issue with strong satellites in the past on a very short cable run.

Putting a wet towel on the LNB/dish *improved* signal quality.

What the... OK, this is stupid...

OK, following my Penta installation on my balcony with a very short cable run to the receiver, I have been having problems with strong satellites, in that the signal reading was reading way below what it should have been. At the same time the weaker satellites have been stronger than they ever...

www.satellites.co.uk

 

[Manikm909]

thanks, yes, i never said the LNB was faulty - i said it was at fault - its just not compatible with my setup i guess