Got a C-Band dish...now some questions

[mikekohl]

Polarizer type feedhorns do NOT have 360° swing in the servo motor; while you can physically twist the device within the collar anywhere you wish, it is generally suggested to point it somewhere convenient that puts the long end of the servomotor pointing to a clock position between 11 and 1:00, as viewed front of the dish.
The reality is that most servomotors have about 120° of range, and you need to rotate the feedhorn so that the 90° swing that you need for perfect selection of V and H polarity falls within that window without hitting the mechanical stops in the motor itself. Failure to do this will cause premature death of the little plastic motor when it cannot stand any more repeated smashing into a mechanical stop.

Not all servomotors have 120 degrees of range...some of the motors used on ADL feeds had as much as 180 degrees of rotation.
Just keep in mind that you should center the feedhorn so that the pattern of travel between V and H never comes close to any limits.

 

[PSB]

Thanks for info Mike

I have a spare one here I was just about to hook up!

Having 2nd thoughts now!

 

[Mr Tony]

Sounds good, berg.

I think I remember you saying that you once had a 10 foot BUD. How come you didn't keep it? Too big to hide from the neighbors' view?

Its still in the garage but its missing parts and is pretty beat up.

 

[Shawn95GT]

oh as for the focal distance....those test cards that I get seem to be the same signal regardless of focal length. I slide the LNB in and out and it stays the same...but like I say its a start...too bad this dang weather is goofy

couple little things.

Sliding the feedhorn in and out changes the F/D setting for the feedhorn. Kind of like wide / narrow on a flashlight. It's pretty much fixed as-per the specs of your dish. Obviously if deviating gets you better signal, more power to you . The 180CM fortec is rated an .38 F/D so you should be able to set that on the scaler ring and be pretty close. Adjust the focal length either by slots in the feed supports, or twisting the scaler ring to bring it closer to the dish. It makes more sense when you see it .

I'm not 100% clear where you set the focal length to, especially on an LNBF. Some say to a fixed distance into the feedhorn. Some diagrams i've seen seem to imply that the flat face (dish side) of the scaler ring is where you measure to. I did this with my 5' dish and it worked out pretty good.

I'm still tweaking the 8' dish, but it is VERY touchy. Very slight changes at the feedhorn swing the quality all over the place.

 

[Mr Tony]

I believe that is a 25 degree LNB. The numbers on the feedhorn correspond to focal depth settings.

DrHydro...on the backside of the scare rings is where those numbers are. The 42 43 on the feedhorn I knew about. The one I have has the same thing

I have my lnb mounted with the LNB at 12 oclock originally, then played with it to get the best signal. The polarotor will help a lot with that, as long as you are in the ballpark you can fine tune it.
Good Luck

how do I know what "12:00" is if the skew is done via the polorator?

Sorry these questions sound stupid

 

[7720driver]

Thanks for the info, Mike. I'm glad you straightened me out on that. Sometimes I make incorrect assumptions.

 

[drhydro]

Physically place the lnb at 12:00 position. Same as setting skew on a KU dish, but instead of using the bottom of the LNBF to mark skew, you will set the lnb (the gardiner box with the big 25) at the 12 oclock position.

Those other numbers "i think" are for intitial skew settings , i wouldnt worry about those, just set the lnb at 12:00 and go from there.

ps: As you and pete have shown with your many posts that are answers to repeat question's, no question is stupid

 

[Mr Tony]

Physically place the lnb at 12:00 position. Same as setting skew on a KU dish, but instead of using the bottom of the LNBF to mark skew, you will set the lnb (the gardiner box with the big 25) at the 12 oclock position.

ahhh..gotcha

Those other numbers "i think" are for intitial skew settings , i wouldnt worry about those, just set the lnb at 12:00 and go from there.

OK cool.

ps: As you and pete have shown with your many posts that are answers to repeat question's, no question is stupid

I know that but I just feel lost not knowing a whole heckuva lot on C-band

 

[drhydro]

And if you think this is fun, wait till you add a polar mount and have the joy of aiming it. It took me many many hours to get my BUD tracking the arc and completely "peaked" in between aiming the mount, finding perfect focal distance, and fine tuning the initial skew (so the servomotor in my polarotor didnt have to work as hard) .

 

[7720driver]

Speaking of lightening the load on the servomotor:

Some analog receivers have a tuning mode that, when you press the up or down channel buttons, it tunes the Horizontal transponders in succession (example: channels 1,3,5,.....23) and then tunes the Vertical transponders in succession (example: 2, 4, 6...24). It other words, it skips every other channel so that the servomotor won't have to twist the probe 90 degrees every time you press the up or down button. This cuts down tremendously on the number of times the servomotor must act.

In Echostar c-band receivers, this mode is called "skip tuning". It might be called something else in other brands of receiers.

 

[rjc3895]

Iceberg
Thought this might interest you

http://www.jaeger.com.tw/tvro/superj..._superjack.htm

There is a US distributor according to the web site. The company makes an H to H and a linear actuator mount for 1.8m and 2.4m dishes.

 

[PSB]

Link seems to be Chinese!

 

[WyrTwister]

Speaking of lightening the load on the servomotor:

Some analog receivers have a tuning mode that, when you press the up or down channel buttons, it tunes the Horizontal transponders in succession (example: channels 1,3,5,.....23) and then tunes the Vertical transponders in succession (example: 2, 4, 6...24). It other words, it skips every other channel so that the servomotor won't have to twist the probe 90 degrees every time you press the up or down button. This cuts down tremendously on the number of times the servomotor must act.

In Echostar c-band receivers, this mode is called "skip tuning". It might be called something else in other brands of receiers.

I think I saw that in a menue on my GI 2730 , never knew what that was for .

Thank you ,
Wyr

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Edited


Place the feed horn so ( with the sat at top dead center - due south ) so the polorotor is at 10:30 o'clock & the LNB at 04:30 o'clock .

You can then set the polarity in the sat menu to +45 degrees & -45 degrees for H & V .

Then , if you peak for skew & you come close to those numbers , you are close enough to being correct on the physical - rotational orientation of the feed horn .

This puts the polar motor at the midpoint of its rotation & it does not bump against its extream left & right physical limits .


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Once you get a digital channel locked in and playing , you can really fine tune the sat east - west position , skew , elevation and focal distance . The digital seems to be more sensitive / critical than analog .

 

[rjc3895]

Link seems to be Chinese!

The company is based out of Taiwan. According to their website, they have a us distributor.

 

[rjc3895]

Link seems to be Chinese!

Oops!

The company is based out of Taiwan. According to their website, they have a US distributor. Go to http://www.jaeger.com.tw/, select products, select satellite TV, select TVRO from left frame, select superjack, select H to H mount or click the distributor link to see US distributor.



Suggested dish size 1.2M~2.4M
Azimuth range 0°~180°
Elevation angle adjustment: 0°~70°
Declination angle adjustment: 0°~24°
1224EL standard, Prime focus dish: 0°~8°
1224EL,Optional, Offset dish: 0°~40°
Voltage: 36V
Current/Max. Stall current: 3.5A
Mounting pole diameter: 50~90mm
Finish: Epoxy powder coating
Sensor available: Reed / Optical.

 

[Mr Tony]

Place the feed horn so ( with the sat at top dead center - due south ) so the polorotor is at 10:30 o'clock & the LNB at 04:30 o'clock .

You can then set the polarity in the sat menu to +45 degrees & -45 degrees for H & V .

Then , if you peak for skew & you come close to those numbers , you are close enough to being correct on the physical - rotational orientation of the feed horn .

This puts the polar motor at the midpoint of its rotation & it does not bump against its extream left & right physical limits .
Once you get a digital channel locked in and playing , you can really fine tune the sat east - west position , skew , elevation and focal distance . The digital seems to be more sensitive / critical than analog .

now you say line it up at 10:30/4:30 but drhydro say line it up to 12:00...so which is it??

The way it looks right now is the LNB if I line that up to 12:00 inside the LNB there is a metal piece (the obvious skew) that lines up also at 12:00 So wouldn't I do it that way if my skew for G4 is +5?

And in the setup for the digital receivr, if its +5, do I set both V & H for +5 or one as +5 and the other as -5?

 

[drhydro]

Polarizer type feedhorns do NOT have 360° swing in the servo motor; while you can physically twist the device within the collar anywhere you wish, it is generally suggested to point it somewhere convenient that puts the long end of the servomotor pointing to a clock position between 11 and 1:00, as viewed front of the dish.

Iceberg i could be backwards as to which position the lnb should be (been a while since i set up my cband only feedhorn), sounds like you want the long end of the probe pointing at "in between 11:00 and 1:00".

As for the +5 / -5, i am not sure about that. Is this on your analog box which is controlling skew?

 

[Mr Tony]

I thought the digital box could do that (pansat 2100 has a spot for polorotor)

Otherwise I'll use the Toshiba...that has auto skew

 

[drhydro]

If your 2100 is at all like my 2700, skew is set under the antenna menu. On the 2700 it starts as 45 / -45 and is adjustable. if your 2100 doesnt have that, then go ahead with the analog box instead for now.

 

[Mr Tony]

yep the 2100 is like an old school 2700 and has a skew of -45/+45