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MY PICS OF MY 4 FOOT MINI BUD WITH THE BSC 621

HEY ICEBERG, HERE ARE MY PICS THAT I TOOK OF MY TEMPORARY ATTACHED BSC621, DONT LAUGH, IT IS JUST A TEMP FIX, I AM LOOKING INTO GETTING A BRACKET FOR THIS TO WORK BETTER.

HERE ARE MY PICS, IT WAS A BIT DARK, DIDNT GET HOME TIL LATE

Well guys and gals I never thought I would ever be sitting here writing a reply to this thread. For serious C band work I personally will never recommend anything smaller than an 8 foot dish...and that hasn't changed. But being disabled I am an advocate of using what you have as opposed to always buying new. I have recently ran in to such an occasion...

I am a regular "listener" to some certain signals down on AMC 8. I would run the dish down to the bottom every morning and run it back up every evening for my sports fix. As I have some 1.2 meter dishes for some of the most important news gathering sats I thought it would be neat to have a fixed dish for AMC 8. I wasn't looking forward to setting a 3.5" pole for a 7.5 ft prime focus I have, so I did some more contemplating and remembered I still have some poles in the ground that will work with an offset dish. I thought what the heck...I'll put one up and just see what happens, and since AMC 8 is on the end of the NA visible arc there shouldn't be too much in the way of adjacent sat interference. I decided to use a Prodelin 1.2 meter dish originally meant for use on DirecWay with an old Zinwell C band LNBF that I have on the shelf. This dish has an extremely large f/d ratio.

I built a holder and installed the dish. I took a Coolsat 5000 preprogrammed with the frequencies I needed up on the hill. The 2 signals of interest vary widely in signal strength so I of course set the receiver to look at the strongest one. I found the sat in just a couple of minutes and peaked the signal. The signal was just good enough to lock so I went to work on the focal length and fine polarity adjustment. I increased the signal by 3 or 4 Q's so I decided to look at the weaker signal. I was disappointed to see that it was just on the border of locking. I peaked and adjusted but that was going to be all it would do.

I thought I would try a better LNB (a Cal Amp Pro II) so I got an old feed and took the servo off so I could manually adjust the probe then put a piece of tape over it to keep it set. I removed the waveguide elbow, which is a trick used to cut down on signal loss. I installed and tested and only gained a single Q. I was glad to get any Q's I could get, and while the stronger signal was functional the weaker (and the most important one to me) was still just on the border. I hadn't been using a scalar plate so next I thought I would play with that and see what happens.

I put the scalar at the point it usually is located on a prime focus and it literally killed the signal. As I moved it toward the focal point the signal improved but it was basically the same as having no scalar. I was observing the Q meter as I was removing the scalar and noticed a bit of a spike at a certain point. I slowly put the scalar back on the feed and when the inner ring was within 1/4 to 1/2 inch of being flush with the end of the feed throat there was a serious spike in quality. I was blown away to see a whole SEVEN Q's increase. This made all signals very useable. I'm sure it would be worthwhile to have a conical scalar plate but right now this is working as good as I need it to.

I guess when you have a need it pays to experiment with what you have and see if it will fulfill the need. No, I won't recommend a 4 foot dish for C band use, but if you are looking for a specific signal or group of signals then sometimes it can be made to work. Here are some pics...please forgive the dirty dish. Notice the position of the scalar where the signal spiked.

Very good work ACRadio, whoda thought it?
Gotta do something about the cows rubbing on the dish though! Spic and Span time.

jamestheman said:

HEY ICEBERG, HERE ARE MY PICS THAT I TOOK OF MY TEMPORARY ATTACHED BSC621, DONT LAUGH, IT IS JUST A TEMP FIX, I AM LOOKING INTO GETTING A BRACKET FOR THIS TO WORK BETTER.

HERE ARE MY PICS, IT WAS A BIT DARK, DIDNT GET HOME TIL LATE

Click to expand...

What is that material you used to extend the Scalar (pics 2 & 3) on the pictures?

ACRadio said:

I am a regular "listener" to some certain signals down on AMC 8.

Click to expand...

OK, you have my attention. What's on AMC 8 thats so exciting to "listen" to? I love listening to radio signals on satellite. If this is not for public viewing then a PM would be grateful. Mums the word and all that sort of stuff.

Thats pretty amazing pulling those c-band signals in on a small dish.
The one thing to remember is the problem with small reflectors is the physical beamwidth of those reflectors at C-band frequencies is quite wide. Meaning you are seeing more than one satellite in a given position.

On Ku band the beamwidth is quite tight. As you go down the spectrum toward c band the longer waves become viewable at wider angles thus negating the need for a larger reflector.

I would imagine the transponders on c-band that are very strong and have a low FEC ratio will come in quite easy on a small dish with c-band.

Its the higher FEC's like 7/8, maybe 3/4 and also while a neighboring satellite is operating the same frequency and polarity will cause you to drop out.

I would be interested in knowing how some dvb s-2 signals respond to 1.2 m dishes on c-band.

I have a 1.2 M prodelin but have never connected it to my pansat 9200 with the s-2 tuner board. I may try that the next warm day we get.


I know my 7.5' prime focus SAMI dish has a beamwidth of 2.1 degrees on c-band. So its slightly over-seeing the desired orbital position.

If i have it slightly bumped too far east or west I can blind scan channels from the neighboring satellite. I would imagine this would be much more severe on an
even smaller reflector.

My 10' dish has a beamwidth of 1.7 degrees on c-band so therefore it sees withing the orbital position of the desired satellite giving a blanket of insulation from
adjacent satellite interference. You can tell it too because it has to be "dead on " to get a signal.
Interestingly enough my 10' can only see 0.5 degree on KU. One bump east or west and you went from 100% signal to 0%.

I bet playing with the scalar rings on the small reflector could yield some different results in helping to block some sidelobes off the dish but at the same time not blinding the lnbf to the point of no signal.

TRG said:

OK, you have my attention. What's on AMC 8 thats so exciting to "listen" to? I love listening to radio signals on satellite. If this is not for public viewing then a PM would be grateful. Mums the word and all that sort of stuff.

Click to expand...

PM sent...