The DirecTV SL3K4NR1-03

[Vipersan]

Ouch ..
My fingers are sore now ..
One Septum gone ..and it wasn't easy..
But ..fingers crossed ...when they stop hurting ..
;)

 

[Vipersan]

You mean physically move the track's dipole round? Or am I on the wrong track? (sorry ;))

Just a thought Llew ..
Maybe I can keep a small section of the copper track seperator and connect the HEMTs input to it ?
what do you think buddy ?
Do-able ?

Or am I just totally mental.

 

[Vipersan]

It would still be pseudo linear ...but would it work I wonder ..
Neither probe would be in the centre of the waveguide ..but still ..
Here is a photo of what I had in mind ..
the modded pcb Ka lnb probe is left of the Ku
rgds
VS

 

[Vipersan]

A better modded photo of my idea with the gnd seperator removed....

 

[Llew]

Not absolutely clear what you're doing there at present VS. You did something similar with your other unit I believe. I'll have to track back to your original mod to wise up.

 

[Vipersan]

Not absolutely clear what you're doing there at present VS. You did something similar with your other unit I believe. I'll have to track back to your original mod to wise up.

No Llew ..
I didn't physically mod the electronics of the older SL3 ..
Simply wasn't possible as the second probe was not in the waveguide chamber ..
This one has both probes in the chamber ...which is why I'm considering the electrical mod as well as Septum removal..
rgds
VS

 

[Vipersan]

Here is an updated image of the old style SL3 with additional commentry ..
Compare the 2 lnb pcbs...
Yes this does provide Pseudo H and V but one of the polarised signals has to exit the chamber to be detected...and the orientation of that lnb is critical..
The new SL3 has both probes in the same plane ..but parallel to the E/W positioning of the dish so placing it at an angle isn't neccessary ..
Hope that makes sense..
My idea for the new SL3 which has BOTH probes within the waveguide chamber is to physically rotate one of the probes through 90 degrees thus having a Vertical and a Horizontal probe..
confused ...well ..so am I
lol

 

[Vipersan]

Ignore ..both of my modified photo images of the NEW SL3 ..
I was in fact looking at the wrong bit of the pcb ..
So a Re-think is needed ...along similar lines though..
Not tonight though ..
My eyes are tired ..that's whay I'm making silly mistakes..

 

[Llew]

Yes, couldn't see why you were adding a probe at the output of the 2nd RF stage, thus removing the feed to the 3rd stage.

Tomorrow's another day VS, better ideas I'm sure.

 

[Vipersan]

Well this is new ...but not what I was hoping for ..
It looks like I've lost the ability to lock the Nag feeds ...on the modified port.
But at first glance it appears I have been successful in boosting the remaining linear polarity ..
Both H and V scans produce similar results but the V scan has the edge ..
It emphasised the Newsnet peaks ..
And or it just got mighty busy round that area ..
5 peaks found
4 feeds ,,,and one data
18511 3300
18516 3300
18528 3300
18557 3300
18561 2500

I'm to some extent happy with this arrangement as I han still use the second port (unmodified) to get a mix which includes the opposite polarity..
I added a a small strip of copper to one of the probes ...and removed the septum of course ..(the additional copper strip most likely doing little actually)
The other port remains as is ..
I'll now refer to this lnb as the Newsnet SL3 I suppose..
and get another on order at some point which will NOT be modded in any way.
Here are some pics and a scan..

 

[Llew]

Those dB levels look quite useful VS. if I can get anything near to that when I get mine, I'll be a happy bunny. The fact is though, if my Norsat can't cope very well with the Newsnet channels, I don't have much confidence. Anyway, it'll be interesting to see what I can receive with the setup.

Regarding modding the probes, I think there would have to be a complete redesign of the layout of the front end, from the probe you were altering to the 1st stage (a 90° shift of the probe), to have any chance of success

 

[Vipersan]

Those dB levels look quite useful VS. if I can get anything near to that when I get mine, I'll be a happy bunny. The fact is though, if my Norsat can't cope very well with the Newsnet channels, I don't have much confidence. Anyway, it'll be interesting to see what I can receive with the setup.

Regarding modding the probes, I think there would have to be a complete redesign of the layout of the front end, from the probe you were altering to the 1st stage (a 90° shift of the probe), to have any chance of success

Totally agree Llew about the probe ....
Such a mod is not at all practical ...but at least this lnb unlike it's older relative can receive one polarity in True Linear..
..without placing it at a 45 degree angle.
I will briefly position it on the dish vertically if possible just to see the opposite polarity Nag feed come in strong.
The search goes on but we at least have _something_
lol

Oh and at one point this morning I did actually grab 5 News feeds plus the data link on a blindscan..
Sadly didn't capture that scan

 

[Vipersan]

You may or may not find this curious Llew ..
I'm having trouble locking ITV Newsnet control room feed on the modified SL3 ..
but only on the F15 ..
Solid lock around 9.7db using the TBS card ..??
I have however managed to lock that news feed that I posted earlier up a photo of earlier using the TBS card ....on the F15 ?
it is HD and 8psk ..and somewhere in Wales ...
They have been there on and off ALL day ..lol
Now ..
Even though the sig level is 9.7 on the newsroom feed it simply wont lock on the F15 since the septum was removed..
I find this VERY curious ...and makes be think maybe there IS something odd about the polarity.
Which we assume to be Linear..
I once posited there may be an element of circular polarisation in the mix ..
OR ...maybe it is linear ..but on an angle ..ie not level..
You have in past commented that you couldn't get a picture using the Norsat ..even though you thought you had adequate signal..?
Now the modified port is receiving True Linear ..much like a Norsat ...I too am having trouble ..but wasn't last night ..pre septum removal.
Curious is it not..
Time to try the Norsat on a tilt perhaps ..?

Not that this would help if as I suspect ..there is a circular element to the Newsnet signal...and that being why the Unmodded SL3 copes better..
In short ..
Don't remove your septum ..you may need it..
lol
Septum being 'nasal' bridge..
So ..when it arrives ..don't cut off your nose to spite your face..
;)

..just ordered a second SL3K4NR1 ..
This one will be left untouched
Thought I'd get in quick as he only has 5 left..

 

[Llew]

Well I've tried tilting the Norsat with the FD1000 feed a few degrees either way whilst watching the Promax spectrum, but the signal just drops below the usual 10dB I normally get (not locking tonight though). Further twisting simply starts to bring up the H carriers, as would be expected with linear carriers.

Also tried the Inverto feed, similar results. Placed a piece of dielectric in the Inverto feedhorn, odd results, had to twist the Norsat a full 45° to get the verticals back (?). Too dark now to continue experiments.

 

[Vipersan]

Well I've tried tilting the Norsat with the FD1000 feed a few degrees either way whilst watching the Promax spectrum, but the signal just drops below the usual 10dB I normally get (not locking tonight though). Further twisting simply starts to bring up the H carriers, as would be expected with linear carriers.

Also tried the Inverto feed, similar results. Placed a piece of dielectric in the Inverto feedhorn, odd results, had to twist the Norsat a full 45° to get the verticals back (?). Too dark now to continue experiments.

Well that theory we can dispense with I guess Llew..
I still think the polarising is odd ..
Probably customised to prevent eavesdropping ..
Is it possible thet use a hybrid Linear/circular variant..
Certainly best results for me so far have been with either of the SL3s ...
The older Pseudo linear SL3 and /or the later SL3 prior to Septum removal..
and in both cases I have locked and had pictures on the F15 above 8db ...9.5 to 10 gives almost fluid motion ..even on the F15.
I suspect you will get results with you DirecTV lnb when it arrives ..
;)

 

[Llew]

Can't wait mate. These particular carriers have been a thorn in my side for too long

 

[Vipersan]

Ok ...As my dish is currently out of commission ..I decided to do some more poking around in this new SL3 ..
I suspect the older version works the same way ..but for now I cannot confirm this.
It would appear that ALL port inputs for signal are active All of the time ..that is to say NOT switched
I guess there was no need since there cannot be crosstalk between polarities when using Circular ..
H/V (Linear) would need a degree of isolation ..
So dealing with only one Ka input port (lnb)
The degree of isolation to be had by using a septum to seperate RHCP and LHCP means the 2 polarised signal drop either side of the septum ..thus one probe collects R the other L ...and therefore no need to turn the mixers or front ends on or off ...
the outputs of these 2 sets of polarised signals make their way to one of the 2 channels of the Zetex 2012 multiplexer chip..
The chip having 2 channels which can be selected either/or internally using the 22khz signal.
So both Left Ka input and Right Ka input lnbs are ON all the time and both receiving BOTH polarities ..
Selection of the wanted LNB is done by internal selection in the multiplexer chip thus ignoring the unwanted signals which also arrive regardless.

Which brings me to the conclusion that although we can use this lnb to receive Linear signals ..it can only work IF there aren't two broadcasts on the same frequency but in directly opposing polarities ...
Providing there is a degree of seperation frequency wise both Left and Right signals could theoretically be collected but since we cannot turn off the unwanted polarity it would be very difficult to decide what polarity the signal ACTUALLY was ..
And since the 2 front end probes cannot be independantly controlled there may be little advantage to opening the whole waveguide up to both probes ..
It might be an advantage to keep them seperate ..but I'm still considering rotating one of them through 90 degrees..
The fact that ALL 3 lnbs and ALL polarities are active ALL the time makes this a very power hungry beast..
I can see why they built it this way ..but certainly not very efficient power wise.

After all this is a multiroom device and having ALL lnbs and probes active all the time means any receiver in any room can access any satellite in the cluster and any polarity on that satellite..without any one receiver having ultimate control..

rgds
VS

 

[Llew]

Yes, I can see the problem (or will do when mine arrives). Maybe there is a way of switching off one polarity, but without being able to look at the actual circuit, I can't help much there yet VS.

I see what you mean about the LNBs being fully active. There again, do you think there may be a way of disabling one or more of them? Again, sorry if I'm a little clueless - until I get one working myself, I'm not going to be of much help.

Does your DR HD or PCI card power up this beast without complaining current wise?

 

[Vipersan]

Yes, I can see the problem (or will do when mine arrives). Maybe there is a way of switching off one polarity, but without being able to look at the actual circuit, I can't help much there yet VS.

I see what you mean about the LNBs being fully active. There again, do you think there may be a way of disabling one or more of them? Again, sorry if I'm a little clueless - until I get one working myself, I'm not going to be of much help.

Does your DR HD or PCI card power up this beast without complaining current wise?

No issues with either the TBS or the F15 ...and do remember when in Ka band A mode ..3 ahave a fully active triple port lnb ..plus..the current drawn by the SUP2400 ..
..they do run warm to the tough ..
ie the SL3 and the SUP ..but enough current must be available ..as I've be running it this way well over 12 months without issues.
cheers buddy ..
No doubt you'll get to contribute to the knowledge base in due course..
;)

 

[Llew]

OK, thanks. Seems they're coping. I'll be able to tell you to the nearest mA what the units are consuming when I check with the Promax - there's a readout on there.