My new LNBF has arrived

[Vipersan]

Hi friends ...
Just waiting for some half decent weather so I can fit and test my latest acquisition.
A friend of mine is currently on a long holiday in New Zealand ....with a view to moving there permanently in the future ..
Whilst there he found a supplier who had stock of the DMS model 13K lnbf with dielectric plate and 3 ring feed plate.
Model BSC421
..and has sent me one to 'play with'
;)
Any of you guys using this lnbf ?
Its much the same physical construction as my Pauxis ...but claims lower K ..and higher gain...
..and the feed plate is definately superior.
Can I expect a noticeable improvement on the Pauxis ?
comments welcomed
rgds
VS

 

[doktorofsat]

Hello Vipersan

13k tells my nothing about the reception performances in C band believe me!

Please upload some photos with your brandnew DMS if I don't ask too much

Only some tests on 24,5 W rtb and ortm mali , nigerian package on 34,5w , ubc on 64E are some weak tp. that can figure out the real value of DMS

Test it with the dielectric plate sugested by me and I looking forward your results ,vipersan


BestRegards
DoktorOfSat

 

[Vipersan]

Hi Doktor..
Just managed to persuade the LNB to pose for a quick photo ..
It's very shy camera shy you know
;)

 

[nelson_b]

hi vipersan --

i will follow with interest your tests with this l.n.b. -- to see how it compares with the pauxis ---

i have seen this-- Model BSC421 -- refered to on some american forums -- but here in the uk and europe we have a lot more circular polarised transponders -- i look forward to seeing how it performs --

i recently bought and fitted to my offset dish a second hand chapparal co rotor - with a gardiner C band l.n.b. attached but that can be talked about in another thread - when i,v done further tests

regards nelson.b.

 

[Vipersan]

Hi Nelson ...
You are correct in that this lnb is from the USA ..but the inclusion of the small dielectric plate would confirm the requirement for use where circular polarisation is the norm.
..so perhaps a little contradictory..
I look forward to an improvement in the weather so I can get it fitted and tested.
I'll let you know how it goes....eventually...lol
I'd also be interested in your results with the corotor ...
I know these devices are very useful ..but I do believe they can reduce overall gain due to insertion losses.
Not important say ...the other side of the pond ...where signal is in abundance ...but over here in the uk ...I suspect a straight feed open throat lnbf is the better option.
Please ..prove me wrong as I too have a second hand corotor that was gifted to me by the same guy who's currently living it up 'down-under' ;)
I haven't used mine as I have no way to drive the tiny polarizing element.
rgds
VS

 

[Vipersan]

Hi friends ...
Some preliminary results on this new lnbf..
The Pauxis was replaced with the DMS ..
No ajustments made or alignment performed ...
I just placed the small slab of dielectric material that came with the lnbf ...into the throat.
I was amazrd to see a fully locked pictures from ERTU at 1West....and intermittent/fragmented images from the Pentagon channel.
I have _never_ had this kind of gain from the pauxis ....
Typically I would get quality around 25 with a fully aligned lnbf with an extended T dielectric ...and similar results with a DOS plate.. on Pentagon
but Im getting around 20 quality with a simple 1 inch long slab of dielectric material ...and an unfucused untweaked lnbf
I can only conclude this new LNBF has great potential...
Hopefully some more coherant results inthe future ....but for now ...its too bloody cold out there..
rgds
VS

 

[Vipersan]

OK ..
I decided to file down the edges of one of my 'T' shaped dielectric plates ...in order that it would fit into the new lnbf..
the guides on the BSC421 being a couple of mm narrower.
That done ..I swung the still unoptimized dish/feed over to 24.5West ...inserted the plate....and scanned for ORTM...
Nothing found..
So tried RTB 4193R ...
I got a solid lock at level 10 quality..
..enough to perform a scan....and was rewarded with a rock solid picture and sound...with a very occasional glitch.
I'm impressed..
I could never get anything from this bird using the Humax HDCI2000 on the global beam.
Odd that I cannot get ORTM ..as I would have assumed the signal levels to be about the same.
I realise it uses the opposite polarity ..somaybe this is a factor?
Differences in power can't be defined from the footprint maps at lyngsat...just a general sense of what to expect.
Nelson ...
..what do you get from this bird ..and at what signal levels ?
rgds
VS

 

[dx qwer]

Hello Vipersan,

I know your DMS C-Band LNB, because I have same here. It performs realy good! So I wish you good reception with it.

Best Regards
Edgar.

 

[Vipersan]

Thanks Edgar ..
As mentioned ..I haven't even aligned and optimised yet ...and yet the signal quality on Pentagon channel at 1 west has gone up from approx 24 - 25 ...to an amazing 31-32.
So far I am very impressed..
rgds

 

[nelson_b]

OK ..
I decided to file down the edges of one of my 'T' shaped dielectric plates ...in order that it would fit into the new lnbf..
the guides on the BSC421 being a couple of mm narrower.
That done ..I swung the still unoptimized dish/feed over to 24.5West ...inserted the plate....and scanned for ORTM...
Nothing found..
So tried RTB 4193R ...
I got a solid lock at level 10 quality..
..enough to perform a scan....and was rewarded with a rock solid picture and sound...with a very occasional glitch.
I'm impressed..
I could never get anything from this bird using the Humax HDCI2000 on the global beam.
Odd that I cannot get ORTM ..as I would have assumed the signal levels to be about the same.
I realise it uses the opposite polarity ..somaybe this is a factor?
Differences in power can't be defined from the footprint maps at lyngsat...just a general sense of what to expect.
Nelson ...
..what do you get from this bird ..and at what signal levels ?
rgds
VS

hi - there - Vipersan --
your initial tests are looking good -- and yes its cold out there tonight --
and the skies are very clear --

ok - about 24 .5 west -- well -- using the pauxis with a bought dielctric plate like you have -- i got nothing

using the pauxis with -my best "Doctorofsat" plate i got both transponders -
with very odd signal / quality readings - but a very stable picture
Using the vantage reciever i got 30 signal strength ( which is below threshold normaly ) and a quality reading of 96 - 98 .

and much to my surprise -- i get exactly the same tonight using the chaparral co rotor -
despite it having a gigantic dielectric plate in the throat and an lnb with a noise temp of 20 k -- maybe its down to having fine control of the skew ?
this C band game is full of surprises

your new l.n.b. will perform well i think once you have it optimised
your 1 west results are good --

regards nelson.b

 

[Channel Hopper]

Vipersan, the di-electric plate should be inserted into the throat at 45 degrees to the rectangular transition to get proper switching of polarities without a mechanical polariser, but I suppose you already knew that

 

[Vipersan]

Thanks CH ...but you can't get it wrong on these lnbfs ...
The throat has preformed slots in the waveguide to enable accurate placing of the plate.
rgds
VS

 

[Vipersan]

Still too cold outside for serious tweaking ...
..a light dusting of snow during the night..
Anyway ..I did venture out with ladders and a tape measure.
I've ajusted the front edge of the waveguide to what I 'believe' to be the correct distance from the dish face centre (81cm as calculated by me last year)
and set the scalar plate to 42 on its embossed scale.. which I believe is closest approximated fd of this dish.
If anyone knows the true figures for a 6 petal solid Alcoa dish I'd be very interested..

Anyway ...didn't hang about in the cold as I suddenly felt the need for a bacon butty..

A quick check on the HDCI2000 on 1 west shows the signal quality to have risen again on Pentagon
..from 31 - 32 on a cloudless day (yesterday) to 35 - 36 today and the skies are no longer clear.

I also checked RTB on 24.5W ..
this too had risen from 10 to 17 ..
Still can't get anything at all on ORTM.
Are the settings at lyngsat still correct ?
If so ..I have a real puzzle to solve.
rgds
VS

 

[Channel Hopper]

If that has been calculated from a dish depth of 25cms then it would be about right on a 1.8m, however from memory the Alcoa was a 6' reflector, or just over 182cms.

You should get the string and measuring stick out.

 

[Vipersan]

Thanks for the reply CH ..
couldn't find any string ...so I used a long straight length of wood ..
Close enough for a quick approximation..
The dish depth comes in at 25.5 cm
the diameter of the dish is 180 cm of useable dish surface ...but measured to the extreme edge of the foldover ..it probably is 182cm +
rgds
VS

If that has been calculated from a dish depth of 25cms then it would be about right on a 1.8m, however from memory the Alcoa was a 6' reflector, or just over 182cms.

You should get the string and measuring stick out.

 

[nelson_b]

I also checked RTB on 24.5W ..
this too had risen from 10 to 17 ..
Still can't get anything at all on ORTM.
Are the settings at lyngsat still correct ?
If so ..I have a real puzzle to solve.
rgds
VS

hi vipersan --

lyngsat listing is still correct --

ORTM is a fraction weaker for me --
one thing i have noticed -- and i dont know why - maybe its peculiar to my setup -------
the 2 transponders are on different polarities and i find that when i have best signal on RTB --- i need to move my dish east about half a degree to get the best signal from ORTM . --- ???

regards nelson.b

 

[Vipersan]

hi vipersan --

lyngsat listing is still correct --

ORTM is a fraction weaker for me --
one thing i have noticed -- and i dont know why - maybe its peculiar to my setup -------
the 2 transponders are on different polarities and i find that when i have best signal on RTB --- i need to move my dish east about half a degree to get the best signal from ORTM . --- ???

regards nelson.b

Thanks for that Nelson..
I'll try shifting the dish a touch and see if the signal comes in...
rgds
VS

 

[Channel Hopper]

The dish depth comes in at 25.5 cm
the diameter of the dish is 180 cm of useable dish surface ...but measured to the extreme edge of the foldover ..it probably is 182cm
VS

From your figures 79.4 cms looks like the right focal distance so you might be over illuminating the refelctor, which can collect unwanted noise from elsewhere (in your case the ground). It is better to slightly under-illuminate on a prime focus for that reason, the s/n will go up.

 

[dinsdale1]

I take it your refer to Mr Roberts? We are the NZ supplier he purchased it from. Cheers

 

[Vipersan]

...hmm..
did he give a first name ?
the initial will do.
rgds