1.2 Meter miniBUD Modified Scalar Ring

[qwert1515]

A few days ago I posted that I could get a DVB-S2 transponder on my miniBUD setup and I was asked to post a picture of my recent modifications to my C-Band scalar ring.

Recently I have read many posts where others who are using miniBUD setups are getting better results with a flat scalar ring versus a conical scalar ring. I am not sure why that is, in theory it should not be the case, and it is not the case for me.

My setup might be an exception because my C-Band LNB is not at the center of the dish. I am using a C-Band LNB with a 17°K noise figure.
I have not tried my modified scalar ring at the center of the dish. When I tried the flat scalar ring at the center of the dish my reception was about the same, as being on the side.

The modification that I have made to the scalar ring is that I have added aluminum foil to the flat scalar ring to make it more similar to a conical scalar ring. I decided on the size of the foil rings by watching the signal quality on a weak transponder change as I changed the size and position of the foil rings.

With this modification my signal quality is much higher (some transponders on the Pansat quality meter go from 30% to 45%) and weak C-Band transponder are stabilized. I can also lock two DVB-S2 transponders with this modification, one with a FEC of 3/5 and the other one with 5/6 (Data transponder). I do not have a way to blind scan DVB-S2 transponder, so I have only tried some transponders that have been posted.

Since I last posted my setup in 2007 (My miniBUD Setup), I have swapped the Universal LNB to a Standard LNB to speed up blind scans and I have swapped the Circular LNB to a universal LNB. (For 53°W and 58°W)

 

[pro96]

nice home made conical.. props

 

[scottc98]

Qwert,

For you non-centered LNBS, are you about 5-6 degs off on each end?

 

[1ADAM12]

Critical Scalar C Band MiniBUD

Confirmed data:
The Inner most ring setting is critical and should be set at the 1/8" depth to lnbf as you have done.
Confirmed by Dreamfox and Walrus1957.
Offsetting the C band lnbf allows to peak the Ku and doesn't harm C band performance.

You might try setting up your flat scalar with this 1/8" margin and then adjusting the whole assembly for max.

Problem with stacked cone scalars is that they become very selective about tp's maxing on one and then lower on another.

 

[McGuyver]

Confirmed data:
The Inner most ring setting is critical and should be set at the 1/8" depth to lnbf as you have done.
Confirmed by Dreamfox and Walrus1957.
Offsetting the C band lnbf allows to peak the Ku and doesn't harm C band performance.

You might try setting up your flat scalar with this 1/8" margin and then adjusting the whole assembly for max.

Problem with stacked cone scalars is that they become very selective about tp's maxing on one and then lower on another.

Can you tell me what effect does the 3/8 drive metric socket have on this configuration and what size is this metric socket? 3/8 drive can be of almost any size socket, the 3/8 is referring to the drive end. And is the socket used as tuning device to be moved around and limited to that particular ring or does one try fitting the socket in the other rings as well? One more thing, can the socket be substituted with other ring shaped metals and is the length and thickness important?

 

[qwert1515]

Qwert,
For you non-centered LNBS, are you about 5-6 degs off on each end?

Yes,
The Universal LNB is a little bit less than 4 degrees off.
The C-Band LNB is 5.5 degrees off.

You might try setting up your flat scalar with this 1/8" margin and then adjusting the whole assembly for max.

I am going to try that, thanks for the idea. I also found this thread which I had never seen before, I am not sure how I missed it
Primestar 84E/BSC621-2 LNBF Experiment I also noticed in that thread that VoomVoom has also posted the dimensions of a commercial conical scalar ring.

 

[1ADAM12]

Non Confirmed Improvements

Can you tell me what effect does the 3/8 drive metric socket have on this configuration and what size is this metric socket? 3/8 drive can be of almost any size socket, the 3/8 is referring to the drive end. And is the socket used as tuning device to be moved around and limited to that particular ring or does one try fitting the socket in the other rings as well? One more thing, can the socket be substituted with other ring shaped metals and is the length and thickness important?

The socket is something that Walrus1957 has used to improve his C band reception. It is not confirmed as an improvement by others to this date. It is like the Minimo BSC621 Ku spacer improvement. Not confirmed by others. That does not mean that it won't work for you, just that no one else has found an improvement.

The socket is a 9/16" wrapped in foil duct tape. and at the 3 O'clock position.
a flat piece of aluminum glued into position may work(?)

 

[qwert1515]

I tried the flat scalar with the 1/8" margin and my signal qualities were actually less than before, so I went back to what I had before.

 

[McGuyver]

The socket is something that Walrus1957 has used to improve his C band reception. It is not confirmed as an improvement by others to this date. It is like the Minimo BSC621 Ku spacer improvement. Not confirmed by others. That does not mean that it won't work for you, just that no one else has found an improvement.

The socket is a 9/16" wrapped in foil duct tape. and at the 3 O'clock position.
a flat piece of aluminum glued into position may work(?)

I tried the flat scalar with the 1/8" margin and my signal qualities were actually less than before, so I went back to what I had before.

Thanks for the update Adam 12, in this hobby it seems that nothing is for certain but the ideas are endless and always worth trying. Experiments may sometimes have dissapointing results but sure fun doing them.

 

[1ADAM12]

MiniBUD Experiments

I tried the flat scalar with the 1/8" margin and my signal qualities were actually less than before, so I went back to what I had before.

Another factor is .5f/d or .6f/d for the flat scalar or conical scalar. Walrus1957 has a GeoSatPro 1.2m.

Thanks for the update Adam 12, in this hobby it seems that nothing is for certain but the ideas are endless and always worth trying. Experiments may sometimes have dissapointing results but sure fun doing them.

Yes, I enjoy a more eccentric view of the hobby. I'd like to see a Little Edison award given for experiments that work. Something placed in the avatar by the moderator.

OBTW, this is what works for me.

 

[McGuyver]

Another factor is .5f/d or .6f/d for the flat scalar or conical scalar. Walrus1957 has a GeoSatPro 1.2m.



Yes, I enjoy a more eccentric view of the hobby. I'd like to see a Little Edison award given for experiments that work. Something placed in the avatar by the moderator.

OBTW, this is what works for me.

Regarding your photo, are you using the C-lnb without a scalar? and is that a Prime* dish and what sat is the C-lnb aimed at?

 

[qwert1515]

Another factor is .5f/d or .6f/d for the flat scalar or conical scalar. Walrus1957 has a GeoSatPro 1.2m.

I am also using the GeoSatPro 1.2m.

 

[1ADAM12]

Mixed Results C band

Regarding your photo, are you using the C-lnb without a scalar? and is that a Prime* dish and what sat is the C-lnb aimed at?

Yep, P*e with Stab H-H. C band most strong stuff 58W to 120.9W

I am also using the GeoSatPro 1.2m.

Be interesting for you and Walrus1957 to compare notes. You are using an approach that he abandoned but got better results. I've attached a photo of the stacked cone scalar that he came up with and others around the world have used to get good results. Photo from Italy.

 

[mr3p]

For you guys with Ku and C band LNBs on the same dish, do you have them going into a diseqc switch, separate receivers or some other configuration. If using a single receiver, are there any issues controlling the motor?

 

[qwert1515]

I am using a diseqc switch, my receiver is connected to the motor, the motor is connected to the diseqc switch which is connected to the four LNBs.

 

[Anole]

tuning the scalar

I think this is more critical on Mini-BUDs, where you are already operating at a disadvantage.

You have to have the feedhorn at the proper focus...
... and ya have to have the scalar at the optimum location for best CNR.
Mounting the two together and moving them as one will cause nothing but grief for tune-up.

Below are excerpts from some comments by two of our more seasoned members.
For the full content of their post, you may click the [View Post] links.

1.2m offset dish and flat scalar:

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.

1.8m offset dish and conical scalar:

Also...one trick with the conical adapter is to FIRST find the signal's focal point hotspot WITHOUT the conical device.
It will be reduced, but you will be rewarded when the conical device is slipped onto the feed assembly.
There will be a dramatic shift upwards in signal almost like magic, when you find it.
Trying to both find the focal point and perfectly adjust the conical ring can result in completely missing the best location due to inadvertently setting that ring near a null point on the feed. It's trial and error, so be patient and organized.

 

[1ADAM12]

For you guys with Ku and C band LNBs on the same dish, do you have them going into a diseqc switch, separate receivers or some other configuration. If using a single receiver, are there any issues controlling the motor?

My setup was a 1.2 m dish with h-h motor and the P* with a h-h motor and a 4 port diseqc switch. One receiver using USALS for the P* and diseqc 1.2 for the 1.2 m. Works ok. I mostly watch the sports on C band and didn't really need the bigger dish or scalar for that so I took that dish down.
So on the P* I have a universal, standard, circular and C lnbf.

 

[walrus1957]

Qwert1515-

Concerning the difference of performance between the flat scalar and the conical feed horn, and my results verses yours. I believe it has to do with the positioning of the LNB. I have always centered the Cbanb LNB on the dish, perhaps if I offset the LNB as you have I would end up with the same test results as you are experiencing.

As to the positioning of the Cband LNB and scalar; I always start by attaching the LNB without a scalar and fine adjust the positioning for maximum signal quality. Then I attach the scalar be it the flat ring that came with the LNB or the conical version, either one is placed on the LNB so that the scalar is flush or extends 1/8 inch further out from the throat of the LNB.

I haven't tried to attach a metal socket to the conical feed horn, but adapting it to the flat scalar improves the signal quality by 5 to 15% across the board for all Cband channels.

To date I have repeatedly tested the 76cm and 1 meter Wineguard, and the 1.2 meter Geosatpro with the conical feedhorn and flat scalar ring. In all cases the LNB was psoitioned in the center of the dish as the sole LNB. And repeatedly I had the best results using the conical scalar (feed horn) on the 76cm and 1 meter dishes. Using the 1.2 meter dish the flat scalar out performed by roughly 5% without attaching the socket, and jumped an additional 5 to 10% using the socket dependent of the channel tested. It seemed to help the lower quality signals the most. Some channels that were coming in at 90% quality, then attached the socket either showed no improvement or may have actually lost a percent or two.

 

[1ADAM12]

Tunning Method for MiniBUD

As to the positioning of the Cband LNB and scalar; I always start by attaching the LNB without a scalar and fine adjust the positioning for maximum signal quality. Then I attach the scalar be it the flat ring that came with the LNB or the conical version, either one is placed on the LNB so that the scalar is flush or extends 1/8 inch further out from the throat of the LNB.

OK, that sounds like something I need to try.

 

[pro96]

A few days ago I posted that I could get a DVB-S2 transponder on my miniBUD setup and I was asked to post a picture of my recent modifications to my C-Band scalar ring.

Recently I have read many posts where others who are using miniBUD setups are getting better results with a flat scalar ring versus a conical scalar ring. I am not sure why that is, in theory it should not be the case, and it is not the case for me.

My setup might be an exception because my C-Band LNB is not at the center of the dish. I am using a C-Band LNB with a 17°K noise figure.
I have not tried my modified scalar ring at the center of the dish. When I tried the flat scalar ring at the center of the dish my reception was about the same, as being on the side.

The modification that I have made to the scalar ring is that I have added aluminum foil to the flat scalar ring to make it more similar to a conical scalar ring. I decided on the size of the foil rings by watching the signal quality on a weak transponder change as I changed the size and position of the foil rings.

With this modification my signal quality is much higher (some transponders on the Pansat quality meter go from 30% to 45%) and weak C-Band transponder are stabilized. I can also lock two DVB-S2 transponders with this modification, one with a FEC of 3/5 and the other one with 5/6 (Data transponder). I do not have a way to blind scan DVB-S2 transponder, so I have only tried some transponders that have been posted.

Since I last posted my setup in 2007 (My miniBUD Setup), I have swapped the Universal LNB to a Standard LNB to speed up blind scans and I have swapped the Circular LNB to a universal LNB. (For 53°W and 58°W)

qwert1515

I was just wondering why you didnt center the CBAND lnb and have the Ku's on the edges?