C-Band in the uk any one useing it

[Vipersan]

I totally agree Paul ..
Of course it depends on you definition of 'massive dish'
As is well documented in this forum ..
I have little or no trouble getting decent cband signals from 55 and 58West on my 1.8 pf
And would therefore assume it would even be possible to pull some of the stronger transponders such as Bolivia TV (55W) on a 1.2m dish
Paul is also right in saying the Harder ...at least for me...C band birds lie on the Eastern half of the Arc ..
And so far the furthest East Cband channel I've picked up is a 'WinnersTV' feed on 62 East ...
Sadly encrypted so I can't even post a photo.
rgds
VS

I think I should clarify and qualify what I wrote ...
The most important thing is clear unobstructed views relatively low on the Horizon both East and West ..
If this is possible ...then Cband on a 'relatively ' small dish should be possible providing care is taken to optimise setup & reception...
..and a good quality Low K lnb does make a huge difference of course..
;)

 

[paulvr]

..and a good quality Low K lnb does make a huge difference of course..
;)

Thanks for your coments, Vipersan. One question: I wanted to buy a Norsat 15 Degrees K but unfortunately the American seller claims exorbitant shipping fees. I bought an MSI C/Ku LNBF from Florida a few years back but that was pure trash, you could either get RHCP and Vertical signals with it or Horizontal and LHCP buth not both and the scalar rings were made out of tunafish can...

The easiest woudl be a purely C-Band LNBF for digital use but I expect that won't be possible because skewing isn't possible to adjust the dipole in the most perfect position with regards to the teflon slab so I assume for fringe reception I'll have to keep using my old Chapparal C-Band feedhorn?

Are there any alternatives to Norsat? I see wild claims that go well beyond 15 K but frankly I mistrust them somewhat after my MSI desaster. I used to be fond of Gardiner LNB's but they seem to habe died and gone to heaven. Any suggestions?

btw: I use Maxplus/Clarke Tech receivers.

 

[Vipersan]

Hi Paul..
You are at the decision point I assume every C band enthusiast reaches I suspect ..
Wether to go for an H/V L/R voltage switched lnbf ....or to stick with that wonderful invention ..the corotor and use a single polarity lnb ..adjusting for H/V L/R by shifting a probe ..
Its a personal choice ..
What I can say is this .
FRom my limited exposure so far to Cband a switched H/V lnbf doesn't miss much ...and skew is relatively unimportant to L/R.
The big disadvantage is of course ..that you have to manually insert the depolarizing plate when switching from linear to circular ..whereas you can still get some sort of signal by tweaking a corotor on linear ..even when the plate is in the way..
My personal favourite switched LNBF so far is the BSC421 ...again imported as no one sold them in the UK.
I have tried a handful of others but this one is stable ..reliable..and high gain..
It claims to be 13K ..and I believe it ..
There is nothing lower out there that 13K as far as switched LNBFS are concerned ..though I believe you can get to 10K if you buy a single polarity lnb for use with a corotor.
As far as skew is concerned using a switched lnbf makes little difference when its rotated in circular mode...and once set up correctly for H/V ..the dish movement compensates automatically for the skew ..and small rotations to correct skew ..although having some minimal effect on the signal ....position is fairly optimal accross the band.
So I conclude ..its a personal preference..
You can tweak that last fraction of signal from your setup with a corotor...but I do wonder if the loss in gain by not having perfect skew ..isn't compensated for my _not_ having to negotiate a rotating probe and omt angles in a corotor..ie an open throat approach.
as to the K factor ..anything less than 15 is good ...
13 is excellect ..
10 is probably the max but not available in switched lnbfs ...and I can't vouch for these claims.

..the lnb(f) s vary considerably in gain and performance ...but anything around 65/70db is good.

I'm happy with my BSC421 ..so much so I recommended it to Nelson ...who bought one ..and was also impressed with the performance improvement.
rgds
VS
;)

 

[paulvr]

Hi Vipersan,
Thank you very much for relating your experiences. In fact, after having posted the question I realized that under your name was also listed the gear you use, so I already went checking. As what I saw seemed somehow related to the horrible stuff I bought before (same nationalistic american label with the three blue stars and red stripes) I felt rather apprehensive but then again your experiences are what counts.

As for me, I used to be a satellite equipment reviewer and tester in the 80´s and 90´s. I´be had a number of dishes from Winegard 180, 240 and 300 cm mesh dishes to Hero 360 cm, with first the fantastic classic Seavey feed and later different varieties of Chaparral Corotor, single C-Band and even single S-band feedhorns.

Reception also included following the Molnya satellites who circulate in an egg-shaped track and broadcast mainly over the North of Canada to cover the borthernmost regions of Siberia using a Hamco-Star later much improved by EGIS robothead with extended horizontal and vertical motor positions. I used the famous NFI sound and video filtering in order to be able to identify even the faintest satellite signals, those typical feeds on Intelsats Global beams on 4166,5 and 4188,5 MHz for instance. Equipment was originally Drake, then mainly Chapparal (Cheyenne, different Montereys and eventually Steve Chilver´s conversion) yet in sensitivity I had the impression that the Echostar LT8700 was the most sensitive/best bandwidth model I used on analogue, at the end I didn´t even have to use my external badnwith filters anymore.

Being specialized in ultra weak analogue signals you might understand that digital C/band pretty much wiped out that part of the hobby for me. Even dish aligning became most cumbersome. For a moment I thought I had a good solution with the Echostar 7000 but then it appeared that that were basically two relatively mediocre and separate receivers taped together. After that I gave up, my C-Band dish stood almost unused for a number of years.

OK, now to the issue at hand: when I started receiving C-Band around 1982 there were only transponders with circular polarization. But even in those days I had to use precision skewing at every satellite position to get the very best of signal. And mind you, that was on a polar mount, initially with an actuator, later with an AJAK H2H mount so theoretically one time positioning of the skew should have covered all satellites, but it didn´t. Especially for those signals coming from the east from say 60° E through 72° E (Madagascar!) quite a bit of polarizer finetuning was mandatory.

That makes me wonder about the statement that with digital transmissions skewing wouldn´t play a major role anymore. After all, digital is merely a transmission technique but as far as I know it doesn´t change anything to the wave forms in which the signal reaches us. The only possible exception I can imagine would be that satellites would now be more unified in their polarities assuming that before they weren´t. But that again doesn´t seem logical because especially the signals from the more extreme eastern positions had a very similar skew regardless if they were Intelsat or others. I alsways assumed it had to do something with the curve of the earth or perhaps even such things as magnetic fields around the earth.

But anyway, back then a skew was essential, also for systems that made the dish curve along the Clarke Belt a.k.a. polar mount.
As far as H/V is concerned, I remember vaguely that i once removed the teflon slab from the feed to see if I would get remarkably better signals from a satellite using linear polarization but that appeared not to be so. Not so illogical because the slab if positioned correctly only crosses the line of signal be it horizontal or vertical by a 45° angle so it shouldn´t be that much in the way.

I checked the BSC421 on the internet and four prices varying from US $12,95 till US $35,- but I guess the hardest thing will be to find a dealer who ships at a reasonable rate. Looking at USPS.com I see that being in zone 5 a 20 ounce package should only cost US $12,48 to send but most companies I contacted wanted amounts varying from 35 till 135 dollars.

Can you do any suggestion as to whom to turn to for getting it at a reasonable price? And about that 10°K LNB to attach to my Corotor, can you suggest a company name and/or firm that sells them? There are so many cheaters and liars on the market....

kindest wishes,

Paul.

 

[Huevos]

makes me wonder about the statement that with digital transmissions skewing wouldn´t play a major role anymore.

Digital uses phase shift keying, but apart from that the properties of the two are pretty much the same.

On a conventional satellite (not SES Astra) H polarisation is parallel with the equator directly below it and V polarisation is perpendicular. A properly set up polar mount follows this closely but there is a very minor error in skew caused by the aerial being located topocentrically, rather than geocentrically.

In theory the LNB skew is irrelevant with regard to circularly polarised signals, and any discrepancies you do see will be due to imperfections in the transmitting and receiving aerials, rather than the skew. I've tried playing with the LNB skew on several satellites with circular polarisation but don't see any signal improvement at all. In the end I just align my LNB for best H/V skew so I could just whip the plate out when not on a circular polarised satellite.

Personally I'm for the easy life so if I were setting up a big prime focus dish for C-band I'd go for a pair of dual polarisation LNBs (one linear, and one circular) and fit them to a siamesed scalar ring. Percentage cross section and offset go down with dish size so the bigger the dish the better with this set up.

As for my own experience with C-band LNBs I'm using Zinwell's which I didn't buy for the K value, but just because they were what my supplier had, and at 12€ each they were well within budget. I'm only using a 1.5m dish with them but am catching a fair range of channels from 57ºE through to 58ºW and limited any further by my local horizon.

 

[paulvr]

Thanks for your input Huevos (doesn´t that mean "eggs"? :-)
I saw the siamese C-Band on an American website but it seems to me that any compromise automatically means a loss. So I´m not too fond of that idea.
I guess your experiences are different from mine with regards to skewing. Theoretically you´re completelt right, the only thing I can assume is that some 30 years ago perhaps satellites were less precize in broadcasting than nowadays. There´s only one way for me to find out: replace the malfunctioning MSI LNBF by a Chapparal C-Band feedhorn with of course teflon slab and my 25°K Gardiner LNB and see if indeed skewing has become a non-issue.
What about the ASTRA stuff: are they polarized differntly from others and if so, is there a reason?

 

[Huevos]

I saw the siamese C-Band on an American website but it seems to me that any compromise automatically means a loss.

Yes, but can you detect it in the real world. Only a decent meter and experimenting will prove that either way. Personally I doubt there would be any noticable difference in C/N.

What about the ASTRA stuff: are they polarized differntly from others and if so, is there a reason?

Astra satellites are skewed 7.5º in relation to the equator. There's a factsheet somewhere on the Astra website that says something about this being so the LNB is closer to vertical in the target locations.

 

[nelson_b]

hi - paulvr -

My first venture into C band was a couple of years go with a DMX-741U Combined C/Ku l.n.b. ----- this was a quite expensive mistake although the l.n.b. holder and conical feed has come in handy since --- (i,m using a 1.8 channel master offset by the way )
next i used a cheap Pauxis 900a h/v switching l.n.b. quite good all round results
certainly better than the DMX was for C band
then i used a second hand co rotor it came with a Gardiner 20k l.n.b. fitted --
i liked being able to adjust the skew for maximum signal although most sats seemed to not need much adjustment - this setup was equal to and sometimes out performed the Pauxis --
i then tried a BSC421 this notably out performed my previous setups and by using a home made "doctorofsat" style dielectric plate pushed the performance a little further
i then bought a second BSC421 for linear transponders as i tired of taking the plate in and out - anything in the l.n.b. throat decreased the signal -- this applied to the co rotor too also as it has a particularly thick plate and would not pick up weak linear t.p.,s
i,v recently made a further signal increase on both BSC421,s by tilting them back to a steeper angle than they were before compared to the K/U l.n.b.
As part of my last USA order and just to satisfy my curiosity i purchased a BSC211 13k
to try on the co rotor -- the results were poor -- it would not even see some very weak transponders that could be seen - "just" - on or above threshold with the Gardiner 20k

in another thread - pride21 - has had good results on his SMW 140 offset dish using a ESX241 h./v. switching l.n.b. -- see here--
http://www.satellites.co.uk/forums/c-band-reception-uk-europe/190629-testing-esx241-lnbf.html
hope some of this info helps you decide which way to go next --
a pic below of my current setup on the old 1.8 channel master

regards nelson.b.