Channel Master/Laminas 1.8m project

I found the Uno tuner to be on par with F15's one - I.e. very good. But yes, it did struggle with some odd transponders. Need to do some more comparisons.
 
OK, so having tried a number of LNB/feedhorn combinations, I think I squeezed as much signal as I can from the Laminas and know what signal levels I should expect across the arc. It's time to try the Channel Master and see how it behaves in comparison. I will be reusing the same PM as I am for the Laminas but need to make a back-plate.

I say "make"... I am going to reuse the one from the Jumbo* and adapt it to the PM. Easy enough - already drilled two holes, which will mount two rose joints for declination and er... well, that's about as much as I need to do!

* looks very much like the back bracket on @John's CM.

2016-09-06 09.54.04.webp

I will be remaking the LNB rotator to fit the CM following testing with original arms.
 
Captain Jack said:
OK, so having tried a number of LNB/feedhorn combinations, I think I squeezed as much signal as I can from the Laminas and know what signal levels I should expect across the arc. It's time to try the Channel Master and see how it behaves in comparison. I will be reusing the same PM as I am for the Laminas but need to make a back-plate.

I say "make"... I am going to reuse the one from the Jumbo* and adapt it to the PM. Easy enough - already drilled two holes, which will mount two rose joints for declination and er... well, that's about as much as I need to do!

* looks very much like the back bracket on @John's CM.

View attachment 97262

I will be remaking the LNB rotator to fit the CM following testing with original arms.
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.... think you have solved a mystery for me there CJ, i could never remember specifically obtaining my back plate (same as yours in pic) and assumed it came with the 2.2 Precision i had. BUT .... i had a Jumbo that got the gears trashed, that went to Scopus Chris for spares, and then on to you i think for spares ?.... BUT---- can't remember my Jumbo coming with the black back plate either!. Well baffled now.
I was always amazed on how it fitted the 1.8 CM fixing holes precisely as well. More well baffled.
A well made substantial back bracket.
 
Chris's Jumbo was/is fully working and seems to be a custom fit to these motors. But a handy back bracket nevertheless!
 
Right - it's up! Looks far more tidy than Laminas bracketry - might need to rework that.

The declination jack point is a little low so will move that to the top bar ... at some point. LNB changer will be fitted in due course. Already fitted the bracing arms (same arrangement as @John's) to take the extra weight.

2016-09-17 15.31.51.webp 2016-09-17 15.31.59.webp 2016-09-17 15.32.09.webp

So, what's it like compared to the Laminas...

1) It's HEAVIER - much heavier. Swimbo helped me carry the CM from the garage to garden and we stopped 4 times. Carrying the Laminas to the garage took one attempt...
2) It's sturdier than Laminas. I took the LNB changer off the Laminas because it was becoming warped with the weight on, even with reinforcement arms. But CM is heavier... so which do you take?
3) Obviously can't fit C band LNBs side by side like I could with the Laminas....
4) Checking signal quality levels across the arc showed that it's slightly lower than what I had with the Laminas (about 0.5dB lower). That said, I haven't spent much time optimising the signal and only tried the GI and IBU LNBs (IBU lost big time). I have a CM feedhorn that I want to try but don't really have many C120 LNBs to play with. Will play some more soon. In the meantime, if someone can suggest a nice C120 LNB that goes well with the CM feedhorn on this dish, I am all ears.

At the moment, because of lighter weight, ability to use it with multiple LNBs without sawing off the arms (LNB ones, that is) and slightly higher signal - the Laminas wins. It's a very, very good dish that should not be underestimated.
 
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Nice work, CJ.

Glad you've got Mrs.CJ involved ........ does she have her own Forum ID yet?
 
The extent of her satellite hobby is helping me carry large dishes to and from the garage. I am paying for that help by having to fit an extractor fan in the bathroom tomorrow ...
 
Teach her how to do it ........ ;)
 
Nice to see you put the winning LNB in the pic! Nice colours as well;)
Orders for Christmas are now being accepted:p

Jokes aside, looking good CJ
 
Captain Jack said:
4) Checking signal quality levels across the arc showed that it's slightly lower than what I had with the Laminas (about 0.5dB lower). That said, I haven't spent much time optimising the signal and only tried the GI and IBU LNBs (IBU lost big time). I have a CM feedhorn that I want to try but don't really have many C120 LNBs to play with. Will play some more soon. In the meantime, if someone can suggest a nice C120 LNB that goes well with the CM feedhorn on this dish, I am all ears.
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Still work in progress but have you seen these comparisons?
Just Sharing This - Invacom 0.3dB vs. Octagon PLL vs. SMW PLL Ku LNBs
and this experiment with illumination although yours seems to have sky behind it so should not be too bad.
Channel Master 1.8 Restoration
The SMW was tested using an IRTE WR75 to C120 transition.
I have yet to try an Inverto Black that people seem to like. My favourite, affordable, C120 is the Invacom. The Octagon is better for frequency stability & accuracy.
 
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Not much choice in C120 LNBs. Inverto Black Pro against Invacom. Invacom is more sensitive but neither is magic. Invacom is better at vertical transponders in my opinion.
 
Thanks s-band and Huevos. I do have an Invacom in the garage. It's years old but last I tried it on my Fibo 90, it worked OK. Will give that one a go. I might also have Black Pro too...

With regards to illumination, sadly, I don't have any noise level measuring equipment to do that, so it's trial and error for me.
 
Got an IBU on my Fibo. Didn't use the flange. Just cut the feed off the IBU and popped it in.
 
Yep, had that too but it failed hence the Invacom.

Found the LNBs along with some Inverto white twin (?)

Not sure why I need 3 CM feedhorns...

uploadfromtaptalk1474137479719.webp
 
My Invacoms are SNF-031. I forgot to mention that they were not without problems. The one I had been using for about 4 years became deaf and especially so on low band such that I changed the switch over frequency before dumping it. It was about 2-4dB down on the one used for the tests which is an older one I found in the shed. I'm using that one now but it suffers from serious microphony on the low band LO. The SNR drops by 5dB or more when the actuator is active (or I tap the dish).

The flange used for the Octagon was from an Invacom that came with a dish. The flange came off when I twisted it to remove it from the feed assembly.
 
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Interesting - tried the 3 LNBs today very quickly and the Invacom was last with 14.7 dB on Astra 4A (11958H), Black Pro was second with 15.1dB and the white Inverto was 15.3dB. All LNBs are very old so don't know if newer ones will be better and we all know that not all LNBs are created equal (even same make/model). But all were very slightly better than the GI one at 14.6dB. I left the Inverto on for now.

This was only on a single frequency all within 2 minutes in partly cloudy conditions.
 
When I was testing I noted that the skew was different for each LNA/B tried, I found that I could get an extra dB tweaking the skew manually on a couple. Looking at probes some were a bit off axis. V & H were not exactly 90 degrees separated on some. The C band Titaniums, especially, vary a lot across the band and between polarisations.

I did some tests comparing SNR with RF level and at 14dB SNR a 2dB change in RF level equated to a 1dB change in SNR. That was with an SR of 27500 3/4 QPSK on the TBS6983. Your 0.5dB SNR may relate to 1dB difference at RF. LO phase noise can also affect the SNR.
 
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s-band said:
When I was testing I noted that the skew was different for each LNA/B tried, I found that I could get an extra dB tweaking the skew manually on a couple. Looking at probes some were a bit off axis. V & H were not exactly 90 degrees separated on some. The C band Titaniums, especially, vary a lot across the band and between polarisations.

I did some tests comparing SNR with RF level and at 14dB SNR a 2dB change in RF level equated to a 1dB change in SNR. That was with an SR of 27500 3/4 QPSK on the TBS6983. Your 0.5dB SNR may relate to 1dB difference at RF. LO phase noise can also affect the SNR.[/QUO
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There should have been some words with that pic above.... They are the probes of a Octagon pll lnbf
 
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