A tricky proposal for 68E

[Vipersan]

Hi friends ..
Always trying to push the envelope when it comes to seeing a little more arc ..
This one is tricky for many reasons ..not least of which is I'm working 'blind' ..at a distance ..
..but then ...I am quite mad ;)
Ok ..here goes

Neither of my 2 usals dishes can be pushed beyond 64 degrees East when using the prime focus ..not even when I switch to disqc 1.2 mode instead of 1.3

They are both on the endstop and maximum mechanical limit..
The TD110 ...cannot be used for 68E as dishpointer indicates the target is literally through a neighbours pitched roof ...
Luckilly ...the Faval 80cm which I have contol of ..is 3 houses away ...and _can_ see 68E as this small shift of about 20 mtrs to the west allows the dish to see the target as there is a gap at the side of the obstruction errr neighbours house ;)
So far so good ..
Next problem is that I only have one feed line to the motor and lnb ...this cannot be further switched by diseqc contol as it already passes through a very complex switch system .
I do however have a cat5 ethernet line ..so in theory can use a dc power injection and extraction system at low current to control an A/B switch which would be between the lnb and motor output.
First question ...are A/B switches suitable for outside locations ?
If so ..on we go..
Next I propose to mount a second lnb alongside the primary lnb a few inches to the west ...in order to gain and extra 4 degrees of the arc to the east ..when the dish is maxed to the limit eastward ..
Hope this is making sense so far ...
Strangly ..it does in my twisted brain ..
So next question ..
In view of info from footprint maps of Intel 10 @ 68.5E it should be possible to pick up at least some txpdrs as the signal is 'claimed' to be approx 42.7 dbw at prime focus ...
..but would an offset lnb be likely to pick up sufficient signal ?

If so ...on we go ..
remember I'd be working blind ..as the dish is quite a distance from the receiver ..
I can get one connected closer ..outside on a nice sunny day that doesn't threaten rain ...but would like to get the installation close before the neccessary tweaking ..
So I need a mental picture of the relative positioning of this additional offset lnb relative to the prime lnb ...which is effectively aligned though of course wouldn't actually be seeing a satellite when on the endstop.
looking at the dish face on ...I imagine the second lnb to the left of the prime lnb and slightly higher so as to get signal beamed to the right of the primary lnb ...coming in slightly lower ..
Have I got this right ?

Ok ..thanks for reading this far ...and any advice or comments ...including ...'you're a in need of therapy'....is more than welcome
rgds
VS

 

[Vipersan]

Well ...
No replies ..but not to be put off I did a little experiment ...and to put it mildly ..I'm gobsmacked..
I may not need to go down the power over cat5 and A/B switchg route afterall ..

Before changing anything at the remote dish ...I inserted yet another switch the opposite way the receivers cofiguration diagram suggests ...but I placed a 4 port diseqc switch _after_ all other switches ..and so is the last thing in line before the motor ..
This switch would eventually end up mounted the other side of the motor ...and thus just switching lnbs ...
I didn't expect the motor control to even reach the motor..
So effectively the receiver has to issue Diseqc commands using 1.0 ...1.1 and 1.3 ...but of course they are out of sequence ..as the 1.0 command is the one controlling the 4 port switch..and thus the lnbs..
Clear as mud eh ?
I was blown away when the remote motor moved !!!
Its a little slower moving than it was previously taking almost a minute to cover the arc ..but that I can live with it..
The insertion losses have mounted up ..by adding yet another 3db loss in the system ...but would this be so critical once the 4 way switch is closer to the remote dish ..?? I just don't know ..
But I can get round this by increasing the dish size from 80cm to 90cm ...which I was considering anyway..

So ..all in all it looks like this project to add a second lnb to the remote dish is viable..
The only problem is that the receiver only issues the diseqc commands once ..at channel selection ..
..and so I have to manually send the sequence again once the dish has arrived at its target destination.. to configure the remote switch to the correct lnb..

Here's a quick diagram stripped down to show the path the signal takes from the remote dish ..
The added 4 port switch has been included but will eventually be moved (see arrow)
rgds
VS

 

[Vipersan]

...btw ..
recommendations of a fairly lightweight 90cm dish are welcome ..
Dont want to overload the motor (Sg2100) ..but of course want maximum achievable gain ..and preferably a dish which lends itself to fitting more than one lnb.
rgds
VS

 

[sonnetpete]

I know my Gibertini XP Premium 1 metre was quite light as it was alu. They also do a neat solution for extra LNB's. I only have the link for my German supplier but at least you can have a look.

_http://www.hm-sat-shop.de/en/antennen-gibertini-xp-premium/

Also Laminas do a 1 metre fibreglass dish but other than the guy in France I use, I don't know where you'd get hold of one. Again a link for info

_http://www.laminas.com.pl/english/index_en.html

 

[Rick]

...btw ..
recommendations of a fairly lightweight 90cm dish are welcome ..
Dont want to overload the motor (Sg2100) ..but of course want maximum achievable gain ..and preferably a dish which lends itself to fitting more than one lnb.
rgds
VS

How about a TD88 VS ? not too heavy and arguably one of the best multi LNB brackets about.,

I like the project. I talked a customer through doing a similar thing to their motorised dish so they could get some of the inclined birds on a seperate reciever yet not alter the motorised.

 

[Vipersan]

Thanks for the suggestions m8's ..
Plenty think about ..regarding the type of dish needed ..
Been up the ladder to confirm the current dish size ..
Its a solid steel 70cm x 80cm ..
but of course that _will_ have to be increased in order to get back the signal I will definately lose fitting the extra switch between motor and lnb(s)
The good news is that it definately works ..
Whilst the ladder was out I did a quick lash up using a piece of aluminium carpet grip strip..
Bent to shape and mounted on the prime focus lnb screw ...so that it sticks out roughly 8 inches to the west of it ..
curled over and gripping on the ALPS lnbs ,,,
Twisted the aluminium strip containing the lnb into a very rough alignment ..but remember ..I'm working blind here ..
I then connected a 4 way diseqc 1.0 switch ...and went back to _my_ house to test it ..
Checked the motor still moved ..OK
Checked the original lnb at the focal point still worked ..OK ..but reduced signal as expected roughly lost 2db
Enabled the 2nd offset lnb through the switch ...and input the Channel 4 transponder details for Astra @28 deg ..
A nice strong reference signal ..
started moving the dish ...and it came screaming in at a very respectable level ..
Ok thought I'd try OTE mux ...39E Hellas2 ..
input the transponder and stepped slowly eastward ..
Not exactly booming in ..but nonetheless a very respectable 5db ..stable and watchable..
So it looks like this project is a go..
I can operate a 4 way diseqc switch .....beyond the motor ....beyond the Smart priority switches ...and beyond the 8 way diseqc 1.1 switch ..
making the remote dish even more versatile and useful...
Assuming I upgrade the dish size ..and get the offset feed(s) correctly aligned.
All new territory for me ..as I don't usually play with offset lnbs ..
but in light of my success with the naked ALPS siamese mounted lnb on my C band setup ..
I think I'm up to the challenge.
rgds
VS

 

[Terryl]

I would get rid of the In-line amp, all they do is raise the systems noise floor, better coax, bigger dish and a better LNB is the best way to insure that the signal from the LNB to the receiver is as good as you can get it.

Besides this is a digital signal, the signal from the LNB to the receiver can be as low as 40% (or lower) with out any undue problems, I have run it as low as 35% without seeing a flicker.

The better the signal off the dish to the LNB the less likely you will have problems.

Offset dishes get the LNB package out of the way of the incoming signal from the satellite and tend to work a bit better on a low level signal.

And a good high quality earth ground (using its own ground rod) on the Dish and system can help a bit, I also put the coax inside of EMT conduit, better shielding and keeps the mice from chewing on it.

 

[Huevos]

I imagine the second lnb to the left of the prime lnb and slightly higher so as to get signal beamed to the right of the primary lnb ...coming in slightly lower ..
Have I got this right ?

It's a motorised dish, right? If so send the motor to zero (due south) and add the second LNB so it is exactly the same height as the LNB in the breech and zero skew. Now, when the dish goes down the arc the second LNB will be almost spot on for skew and alignment.

 

[rolfw]

...btw ..
recommendations of a fairly lightweight 90cm dish are welcome ..
Dont want to overload the motor (Sg2100) ..but of course want maximum achievable gain ..and preferably a dish which lends itself to fitting more than one lnb.
rgds
VS

The Penta 85 Aluminium is a good dish, will certainly perform as well if not better than any of the other 90cm dishes around and OK for offset LNBs, if you add an Inverto Black Ultra to that, it should work well..

 

[nelson_b]

hi - vipersan -
as you know i had an old 90cm x 80cm mesh fixed dish on this sat a couple of years back to recieve - SABC news - sadly not transmitting from there now - so the dish has been taken down now
i was just using the 1 - ln.b -- it was a Edision 0.3 and was a particularly good match on that dish - the signal was weak generaly - and although it was ok in good weather on standard cable - it was improved somewhat by using c.t. 125 -
it was a 65 metre cable run -- and just went through a 1x8 diseqc switch at the reciever end -- the signal could still fade in and out though in cloudy and damp weather - and vanish altogether when raining -- one of the better signals came from - transponder - 12575 V
DVB-S/MPEG-2 3378 3/4 ManaSat 1

regards nelson.b.

 

[Vipersan]

I would get rid of the In-line amp, all they do is raise the systems noise floor, better coax, bigger dish and a better LNB is the best way to insure that the signal from the LNB to the receiver is as good as you can get it.

Besides this is a digital signal, the signal from the LNB to the receiver can be as low as 40% (or lower) with out any undue problems, I have run it as low as 35% without seeing a flicker.

The better the signal off the dish to the LNB the less likely you will have problems.

Offset dishes get the LNB package out of the way of the incoming signal from the satellite and tend to work a bit better on a low level signal.

And a good high quality earth ground (using its own ground rod) on the Dish and system can help a bit, I also put the coax inside of EMT conduit, better shielding and keeps the mice from chewing on it.

Hi terry ..
I am going for a bigger dish but not huge....
As to the line amp ..
The whole system fails if it is removed ...I've already tried ..
The motor still moves of course ..but little or no signal from anything other than the strongest sats ...and that using the prime lnb ..
My guess ..
Its boosting the signal which was fine before entering the complex switch sustem ...making it sufficient to negotiate the switches and still produce a fair outout ..
Certainly at this point removing it isn't an option...maybe after the dish upgrade ...but I'm not hopefull .
..Its a long cable run 35 mts may be a bit conservative..
rgds
VS

 

[Huevos]

Its a long cable run 35 mts may be a bit conservative.

If that is just over 35 metres and needs a line amp I'd say the cable is knackered. Even for runs well over 50 metres I rarely see a difference in MER comparing metering at the LNB to metering at the end of the run. Of course gross signal is lower but normally well above the receive threshold of the tuner.

 

[Vipersan]

Hi Huevos ..
Even if the Cable ...which is original brown copper foil on copper core is knackered ..installed almost 20 years ago in the days of squarials
its impossible to change it ...as it runs through lofts from my house to my dads..
There are no joints ...and providing I remove all switches ..ie ..straightfeed lnb/dish to receiver ..with no motor in line ...I get a strong more than adequate signal..
Only when the switches are introduced does the signal fall ..
The amp appears to be compensating for the (multiple) switches and the motors effects on the signal degradation.

just out of curiosity ..whats the longest cable run you've encountered which passes the signal through ..say 4 switches and a motor ...each claiming 3db signal loss ?
rgds

 

[Huevos]

just out of curiosity ..whats the longest cable run you've encountered which passes the signal through ..say 4 switches and a motor ...each claiming 3db signal loss ?

I don't know. On my "tuner A" on the Duo I've got some runs around 40 metres total that pass through 1 committed and 2 uncommitted switches then the V-box, then the Vantage x221 (for when I want to do blind search blind search) and finally loop into the Duo. Sometimes I add a splitter with a DC blocker so I can plug in my spectrum but still have the receiver in control of everything.

 

[Vipersan]

It could well be that the cable has deteriorated over 20 years ...but since its isolated in lofts ..its hard to viualise this..
but of course it could well be kinked or somesuch ..
Nonetheless its what I have to work with ..so I'll have to make the best of it.
No doubt a bigger dish will help ..though I'm undecided wether to push for a full 1m ..say an orbital ally ..
..or the much recommended TD88 ...which is presumable 88cm x 78 cm or thereabouts...in reality..
The orbital is an option ...but not sure if they do dedicated multifeed adapters for this one ?
rgds
VS

 

[Vipersan]

..couldn't take photos last night as it was getting dark ..
Here are the snaps to go with the lash up ...
I suspect the distance between the 2 lnbs is greater than actually needed ..but I was in a hurry to test it...
..just to prove it was viable..
rgds
VS

 

[A nonymous]

I can confirm that you can get quite a good signal on a Fracarro Penta 85 in the UK

Didn't think i'd get this bird with it being so low on the horizon in my location

Anyway here are some screen grabs for you enjoyment

Nano

 

[Vipersan]

Ok ..made a snap decision based on price ...and the having it on-site over the weekend ..
Contacted my local sat-shop ..
And explained what I wanted ..
Ian the owner had the TD88 in stock ...but in steel only ..
Not that its a problem providing its not too weighty ..
Went up and picked one up ..physically ..and decided it was light enough and weight wasn't an issue ..
Also got a 4 lnb multifeed kit which he also had in stock
So dish and matching feed plus a handful of F connectors ..
£55 all in with trade discount of course..
I'm well pleased ..and hope to get the dish up this weekend..
rgds
VS

 

[Lazarus]

Looking forward to the next chapter ......................




PS: Is your PM Inbox full?

 

[Vipersan]

Cheers Gordon ...
dumped half a dozen as a quick fix ..
I'll have a proper clearout when I get round to it..
rgds