Circular with a linear LNB

[123tim]

I'm stealing a quote from Pete posted in Gary Z's post "Help with G10 R." in order to ask a question.

Talking about picking up circular transmissions with a linear lnb Pete said "As above it looks like 119ºW, remember it is possible to pick up some circular signals with a linear LNBF!

For example I get NASA but can't get GOL TV (With a linear LNBF), depends where you are in the country."


How is it possible to do this? Is the NASA signal so strong that it can bleed over into the linear LNB circuitry?

Why is location a factor for reception? Is this also a level question?

Thanks for any reply.
Tim

 

[Mr Tony]

Tim
When you do a blind scan, depending on the receiver, it can go from 11.7-12.2 (normal KU) or 11.7-12.350

My Pansat blind scans from 950-1600 IF freuqency (add 10750 and thats how you get your numbers). When I scan 119 with a LO of 10750, it does pick up the first little batches of transponders on Dish 119.

Universals do the whole high band spectrum (11.7-12.75) so I remember when I'd scan 83 I'd get a few TP's on 83 and all of them on 82

 

[123tim]

Iceberg,

Sorry for taking so long to reply. It's been taking me a while to digest this.

I don't think that I understand this very well, so I'm not going to be asking very intelligent questions. Sorry about that.

I understand about the IF frequency, but I seem to be missing something important. I know that Nasa is at 12370, but I'm not making the connection of where it is on the frequency range and how it can be picked up with a linear LNB.

So, is this more a question of frequency range, rather than the polarization of the LNB?

Sorry to be so dense.

Thank you.

 

[Stats8]

The signal will be degraded when you use the wrong lnbf for the signal.
You will get a signal, just lower level, that will possible mean no picture on weaker transponders

 

[TiminMb]

When I wasn't aware of what the various settings were on the blind scan function, I did a scan for "all" instead of just FTA on one of those encrypted satellites (I was looking for NASA channel) and it came up with the names for a hundred channels that were encypted, and no doubt cicular polarity. But when I set my scan to the transponder frequency for NASA channel, I don't even get a blip on the signal meter. Must be weaker for me here up North.

 

[No Strings]

Circular polarity signals do show up on linear LNBs.

Neal

 

[Mr Tony]

no strings

They do show up on scans. When I scan Galaxy 11 or AMC9 on my Pansat I get on the scan TP 1-9 of the DBS slot (ExpressVu 91 or 82) on the receiver....lots of scrambeld stuff

PSB can get NASA with a linear (although at low signal)

 

[No Strings]

no strings

They do show up on scans. When I scan Galaxy 11 or AMC9 on my Pansat I get on the scan TP 1-9 of the DBS slot (ExpressVu 91 or 82) on the receiver....lots of scrambeld stuff

PSB can get NASA with a linear (although at low signal)

:up

And since DBS satellites run higher power than 11.7 - 12.2 birds, Nimiq1 will accually show up with HIGHER signal levels than G11 will on my linear Ku systems/spectrum monitors.

Neal

 

[Tron]

Unfortunately, a linear LNBF will often pick up circular signals, even from adjacent birds. I get Dish 119w crud mixed in every time I blind scan Satmex 5...

 

[123tim]

Unfortunately, a linear LNBF will often pick up circular signals, even from adjacent birds. I get Dish 119w crud mixed in every time I blind scan Satmex 5...

This makes me want to try the Circular to Linear conversion (that charredpc posted) all the more. Has anyone tried this lately?

 

[SatelliteAV]

There is approximately a 3dB loss (50%) when receiving circular polarity signals with a linear LNB and visa versa.

 

[123tim]

Cool! If that's all of the loss that you get with the lnb unmodified, then the loss for a circular to linear conversion might be better than I thought. (Link to conversion found here: http://www.satelliteguys.us/showthread.php?t=30837. ) To my surprise, it's getting hard to find a source for old (free or cheap) circular lnb's. (At least for me) Our local cable company removes dtv and dish network antennas and lnb's in order to destroy them. They had about twenty laying in the shop when I was there. Company policy won't allow selling or giving them away.

 

[Mr Tony]

Tim do you need some? I'm sure that can be arranged. I have "a few laying around"

 

[scottc98]

Company policy won't allow selling or giving them away.

If only they just threw them in the trash. then you could "dumpster dive"

 

[Mr Tony]

Dumpster Diving and Junkin...words I love to hear

 

[Tron]

Most of the newer Dish and Direct dishes (the DishPros and the Phase IIIs) don't work well for FTA, and the older ones (with single LNBs) are getting hard to find. Just looking around here, most dishes are Phase III (DirecTV) or DishPro (Dish). Then again, many older dishes were destroyed by Katrina, and people have had them replaced.

 

[jgbayless]

I use 2 LaVa 0.3 lnbfs for t5g turn 12 o'clock position & g10ku I had to turn lnbf to about the 10 o'clock position to get the weaker transponders. Check out ebay Item number: 5784782663 for this lnbf details. around 12 bucks a piece. I bought 4 of these a couple months back are using 2 right now though. You have to turn on 22 kHz for these to work.

 

[PSB]

We actually prefer people buy from our GOLD sponsors here!

"Please Support Those Who Support Us!"

 

[jgbayless]

Sorry about that, Duely noted. I only ment to show reference about what lnbf I had and they were cheap to comeby. I did not mean to steer business any direction.

 

[PSB]

Don't be alarmed just keeping our sponsors sweet