The DirecTV SL3K4NR1-03

[Llew]

That sounds about right, an improvement of maybe 1dB considering you've not presumably adjusted them while checking for max level. I'm sure there's much more we can do regarding best 'lens' positioning do you reckon?

 

[Vipersan]

That sounds about right, an improvement of maybe 1dB considering you've not presumably adjusted them while checking for max level. I'm sure there's much more we can do regarding best 'lens' positioning do you reckon?

Yep ..I figure there is more obtainable ..but without a decent meter ..such fine tweaking is out of my hands ..
Over to you buddy..


..btw ..been monitoring the newsroom feed for a short while now ..
Carl hasn't been moved so comparisons are accurate..
signal dropping ever so slightly now about 8.9 to 9.2 db variance ..with occasional BER reports
..and very occasional picture freezes ...but still mostly fluid.
Much thick cloud has gathered ..so rain imminent..
I'll continue to monitor as the signal degrades..
There's that phrase again..
Not an exact science..
lol

 

[Llew]

Hi VS
I removed the septum from the left hand port and put everything back together - only to realize I hadn't removed the horizontal planes from the PCB
Is this absolutely necessary in this mod?
Cheers.

 

[Vipersan]

Hi Llew ...
I haven't found it neccessary if the entire lower chamber below it is opened up ...
ie that partition directly below it in the casting that screws through the pcb and covers the electronics ...
if this partition is left in place then the horizontal planes of the pcb which you are referring to (connected to ground ) effectivelyalso ground this partition thus dividing the square resonance chamber into two rectangular sections pertaining to the two probes ..
Hope that makes sense ??
My pcb is still intact but signals reaching the chamber under the pcb around the Hemts are free to circulate..
I do hope this mod is beneficial for you ...
I gained about 1 to 1.5db ...but certainly it didn't reduce the db levels.
Removing the Septum is what memoves the Horizontal signals ...removing the partition allows 100% of the captured signal reaching the bottom of the lnbs chamber to circulate freely below the pcb.
The mod still works with just the septum removed ..but still to some extent divides the signal between the 2 probes.

rgds
VS

 

[Llew]

OK, I might do the chamber mod. At present, the Teleippica H carrier has disappeared, but Newsnet peaks are lower now than before, certainly compared to reception on the unmodified port.

 

[Vipersan]

Here is a crude and much simplified diagram of what I refer to ...

 

[Vipersan]

Sorry to hear about the reduction Llew ..
I didn't experience any reduction ..
As I said I DO hope you benefit from this mod ..but even if you don't the other lnb should not suffer ..
Perhaps you can move the dish 3 degrees ..and compare the 2 lnbs directly ..
modded and unmodded.
I would be gutted if your progress is affected ..
But you still have the other ..and that should NOT be affected at all ??
rgds
VS

 

[Llew]

Thanks, the picture makes it clear what needs to be removed, as I hadn't checked the chamber when it was disassembled.

Oh well, a job to do on a rainy day I think.

 

[Llew]

Sorry to hear about the reduction Llew ..
I didn't experience any reduction ..
As I said I DO hope you benefit from this mod ..but even if you don't the other lnb should not suffer ..
Perhaps you can move the dish 3 degrees ..and compare the 2 lnbs directly ..
modded and unmodded.
I would be gutted if your progress is affected ..
But you still have the other ..and that should NOT be affected at all ??
rgds
VS

Yes, maybe I'm not aligned right on the dish. It was a quick check before it got too dark.

 

[Vipersan]

Ok ..not the best time of night to try this ..but I first tried to lock Newsroom feed on the modded lnb port as before ..
Tricky to lock using the TBS card atm ..but lock it did at 8.2db
Tweaked the dish AZ EL ..and this was max ..
Not an ideal comparison I know as the second unmodified port is a further 3 degrees away from the focus ...but you would imagine still lockable ?
Nope ..not a chance ..
the best I could achieve on the unmodded still circular polarised port was 4.2 db ..after tweaking AZ and EL
So only three possibilities ..
either that extra 3 degrees is subtracting around 4db ...? 1db Id accept due to the additional 3 degree offset but 4db seems a bit much..
OR the mod is working as it should ?
OR the second unmodified lnb has gone faulty in some way..

So to test if the lnb was still working I attempted a lock on Teleippica with the unmodded lnb ..
not the strongest of locks ..but lock it did at 7db (keep in mind the additional 3 degree offset)

 

[Llew]

That seems a fair test. Tomorrow I'll do the same , but with sliding the LNB from one port to another, easy with the LNB on my multi-LNB 'tramline'.

 

[Vipersan]

That seems a fair test. Tomorrow I'll do the same , but with sliding the LNB from one port to another, easy with the LNB on my multi-LNB 'tramline'.

I await your results buddy with interest..
We do have fun dont we ..
lol
In a perfect world ...the magic number 3db is what should be gained by the conversion ..but the world aint perfect ...the lnb isn't designed with linear in mind ..but I WOULD have expected at least 1.5 if not 2db of extra gain for vertical reception ..and an almost total removal of horizontal...

 

[Llew]

Did a port swap-over test VS.
Worse dB levels on the port with septum removal, 2dB lower on Newsnet
There's still the horizontal component showing, so I think it needs more than just removing the septum.

 

[Vipersan]

Did a port swap-over test VS.
Worse dB levels on the port with septum removal, 2dB lower on Newsnet
There's still the horizontal component showing, so I think it needs more than just removing the septum.

What can I say Llew ..
Sorry buddy ...
You might as well remove that partition and see if you get back what was lost ..
Nothing to lose now ..
but be careful with the removal ..
dont damage the chamber walls.
rgds
VS

 

[Llew]

OK, that'll be a job in waiting. Meanwhile, I'll carry on trying to squeeze out more signal on the unmodded one (given that there's only so much a 1M dish can collect with these carriers).

 

[Vipersan]

This explanation may sound a fanciful Llew ..but hopefully makes some sense ..
In my addled old brain it does..
The probes are etched onto the pcb ..opposite sides of the partition..
The partition was originally the lower extension of the Septum ..(now removed ..)
Thus the septum effectively passed through the pcb and on into the lower bisected chamber..
Signal is seperated into R and L and drops either side of the septum ..and thus either side of the partition in the lower chamber.
The pcb probe is on the underside of the board metal strip facing into the chamber(s)
signal still divided in half assuming signal enters both halves of the bisected chambers ..bounces off the bottom and side walls and mostly collected by the probes on the return ...as they face into the chambers.
Some signal would be collected on the way in ..or down the waveguide ..but this signal would have to pass through the pcb to get to the probe ..
Thus somewhat reduced in the process..
So effectively we still have the bulk of the signal divided in 2 to be collected by the 2 ..now vertical only probes...after having bounced inside the 2 half chambers.
A small amount of signal having been collected by the probes having passed through the pcb material.
My belief is ...and I hope I'm right that removal of the partition barrier (ie septum continuation ) makes the lnb behave more like a conventional Linear lnb..
Personally I think a circular lower chamber and waveguide would be more successful in this process ..but ..
we can only play the hand we are dealt.
I hope some of this makes sense.
rgds
VS

 

[Llew]

Yes I think I follow your line of thinking, it's just the way the chamber has been designed solely for the DirecTV services. What you've done with the chamber is probably the best that can be done to maximise those vertical transmissions on 19E.

If I get a spare SL3, maybe I can follow through with more experiments in that area - I think taking apart the one I've got too many times will eventually ruin it, knowing my luck

 

[Vipersan]

Yes I think I follow your line of thinking, it's just the way the chamber has been designed solely for the DirecTV services. What you've done with the chamber is probably the best that can be done to maximise those vertical transmissions on 19E.

If I get a spare SL3, maybe I can follow through with more experiments in that area - I think taking apart the one I've got too many times will eventually ruin it, knowing my luck

..and the reason I bought a second unit ...in case I too burgered it up ..
lol
btw ..complete disassembly isn't needed to remove that partition ..
Just the half dozen screws holding the casting to the pcb ..
so ..not anything like as difficult as septum removal ..
pcb doesn't have to come out again ..
;)

 

[Llew]

Of course, it's the casting over the PCB

Cheers. Not such a big job then, just some grinding tool like you used perhaps, and some elbow grease.

 

[Vipersan]

Of course, it's the casting over the PCB

Cheers. Not such a big job then, just some grinding tool like you used perhaps, and some elbow grease.

Like I said Llew ..
you've nothing to lose now ..and hopefully a lot to gain.
Fingers crossed you get back what you lost at least..