120cm dish with C-Band performance - Now with HD!

[spindoctor]

hello FTA pioneers .......first post

you are GREAT

anyone have success with AMC12 C BAND with 1.2M OFFSET dish

larger?
CASCADE? can you please check if possible?

thanks a million john

 

[Cascade]

Hi John, welcome to Satelliteguys FTA
Unfortunately I can't do a thing right now, my meter bit the dust earlier this week so I'm stuck on the preprogrammed sats I have stored in my motor.

As soon as I have a meter I'll be testing more, I don't think I have a view of AMC12 (trees) but I'll try.

 

[spindoctor]

thanks for your quick reply CASCADE

trees ..hah cut those damn things ..ha ha

you should see mine 80ft and still growing....

 

[tdti1]

The Greek mux on AMC-12 comes in great for me very strong, so if those are the feeds you are looking for hope you can get them with a smaller reflector.

 

[spindoctor]

tdti1

HELLO

yes those are the feeds i was thinking.

so you are getting them with a 10.5' dish wow


anything smaller

 

[n4bbq]

Ok,

I mounted my C-Band LNB on a 120cm dish (122cmx132cm) yesterday and have a bit of data.

Analog Results on AMC3:
Doc Scott on TP20. Doc was watchable. The picture was fine but there was a lot of noise there. The audio and color quality was fine. There were two NTSC feeds being used that were in the clear and as crisp as if I had been on a 10 foot dish. Two scrambled analog channels were clear, but most had noise in the picture.

Digital:
I did a smart scan of AMC3 and came up with three transponders. All the channels were scrambled and the quality of the best one was 30% and the worst one was about 14%.

This antenna was a fiberglass one (no name I could find that we use to receive GPTV on Ku band). I would ASSUME that a solid metal dish will have a lower noise temperature and maybe a tad more gain, but the gain would be slight if any.

We also have a 10 footer at another location. I'll go over at lunch and smart scan AMC3 on it and see what pops up and post the difference in this post.

Edit: Well as most of you probably already know, the quality was >80% for the three transponders that I mentioned earlier, and a whole lot more popped in there. Of course, AMC3 hasn't got a lot of good stuff, with the exception of Doc Scott on TP20! I really would like to have the analog feeds on the C-Band birds and I can see from about 75W to 140W from one spot in my yard that may end up housing a 6-7 footer. Time will tell and I have a C/Ku Chaparral LBN, a motor, the hardware, all I need is a dish...

 

[rkrenicki]

I am thinking about PAS-9 @ 58.0W at the moment.. is that even in your field of view?

http://www.lyngsat.com/pas9.html it has NHK

 

[vj9999]

I locked in on NHK last night and it had about 50% signal quality, but picture was breaking up and unwatchable.

 

[vj9999]

Here is some finding with AMC12 and Greek Mux. Last night with the scalare ring on about half way down I was getting 55% signal quality. This morning without the ring I was getting 45-50%. Right now with the scalar ring on the very edge of the lnbf I am getting 74% signal quality!!

Not bad

 

[Rick in MD]

Do you have pictures of what you have done with the scalar ring, and do you know why it would have such an impact on quality?

 

[vj9999]

I don't have pictures (I can take some tomorrow). My guess is that since 120 cm dish has beam width of about 4.5 degrees (edit: it is 4.5 degrees for c-band for ku it is around 1.5 degrees), it helps narrow it down a bit?! I read (or tried to read)on one of the german forums that came up on google that scalar ring for offset dishes should be more like funnel shape to help narrow the beam even more.

I'll see if I can find a picture of that lnbf/scalar ring.

edit:
here is a link to Chaparral offset lnbf picture:

 

[PSB]

Sounds right, I am not having much luck since removing my scalar ring, one or two TP. were better but most were down on signal quality!

Thanks for the input/picture vj9999

Back on goes the scalar ring!

 

[Sadoun]

vj9999

Very good point about the scalar rings.

 

[vj9999]

Here is the link to german forum talking about this http://board.satbook.de/wbb/thread.php?goto=nextnewest&threadid=1049&

There is another picture of he offset ring in second post and I think he is saying that he gets 20% better signal than with the scalar ring for prime focus.

 

[scupmando]

If Sadoun can supply a c-band lnb that'll work fine with the 120, then I'm upgrading my dish! Great work guys!

 

[Cascade]

http://www.satelliteguys.us/showpost.php?p=511869&postcount=42

http://www.satelliteguys.us/attachment.php?attachmentid=4607

That's how I had mine.
vj9999 - take your sigmeter and loosen the bolt or screw holding the scalar.
Slide the LNBF back so it's 2" away from the rear of the dish/ring (In mid air) and let me know what signal readings you get from the meter.

 

[Rick in MD]

I don't have pictures (I can take some tomorrow). My guess is that since 120 cm dish has beam width of about 4.5 degrees (edit: it is 4.5 degrees for c-band for ku it is around 1.5 degrees), it helps narrow it down a bit?! I read (or tried to read)on one of the german forums that came up on google that scalar ring for offset dishes should be more like funnel shape to help narrow the beam even more.

I'll see if I can find a picture of that lnbf/scalar ring.

edit:
here is a link to Chaparral offset lnbf picture:

Thanks.. Interesting thoughts..

 

[n4bbq]

Here is some finding with AMC12 and Greek Mux. Last night with the scalare ring on about half way down I was getting 55% signal quality. This morning without the ring I was getting 45-50%. Right now with the scalar ring on the very edge of the lnbf I am getting 74% signal quality!!

Here's a note from Chaparral's Web Site on Scalar Rings

http://www.chaparral.net/ts_feeds.html

 

[vj9999]

That's how I had mine.
vj9999 - take your sigmeter and loosen the bolt or screw holding the scalar.
Slide the LNBF back so it's 2" away from the rear of the dish/ring (In mid air) and let me know what signal readings you get from the meter.

I don't use any signal meters. I built a BLSA few months ago and it has been the best investment I made. Nothing beats a spectrum analyzer and when it is cheap and good like BLSA

I'll give this a try later today and let you know.

 

[Cascade]

We could always ask Devo to lend us their hats if a funnel-type scalar ring is needed:

http://www.vh1.com/shows/series/100_greatest/one_hit_wonders/img/devo_main.jpg
http://www.devobook.com/domes.jpg