GEOSATpro CK1 installation question

[skysurfer]

I decided to break out this feedhorn and put it on one of my C-band dishes that I don't frequently use in day to day satellite signal watching.

There were no instructions so I installed it similar to a Corotor feedhorn that I am used to installing. I wasn't too impressed with the signal level results after I installed the Geosatpro CK1.

Does f/D matter? I don't see any markings on the throat to determine how deep to insert the throat into the scaler ring before tightening down.

Are you also supposed to make the focal length from the base plate of the dish to 1/4" inside the edge of the throat of the feedhorn or is there some other measurement point for focal length?

Polarity was easy and straightforward since you can see the probes so there are no questions about that.

 

[Corrado]

Perhaps you could try to match the existing f/d setting. the Index mark should point up for zero skew. The photo is from a post from Brian at Satellite AV.

 

[Mr Tony]

I would make it the same as the existing LNB is set up and work from there. I know when I got my 621-2 I had issues but then patience helped me get it to work pretty dang good now

 

[skysurfer]

I would make it the same as the existing LNB is set up and work from there. I know when I got my 621-2 I had issues but then patience helped me get it to work pretty dang good now

The LNB I am replacing had its throat stick out about 1" beyond the scaler ring looking into the dish.

Are you suggesting I take the geosatpro and bolt it to its scaler ring with about 1" extending out and the put that on my dish and set focal point so that the focal point is 1/8" inside the front lip of the feedhorn throat, very similar to how I had my previous LNB installed?

Thanks.

 

[Mr Tony]

I know on my 621 the LNB sticks in about an inch from the scaler rings (inch farther towards the dish)

 

[bloomdog]

Does f/D matter? I don't see any markings on the throat to determine how deep to insert the throat into the scaler ring before tightening down.

.

From my research and experimentation with my mini BUD and C Band reception, f/D and placement of the scalar ring is very important. What is the f/D for your dish? What are dimensions for your waveguide? How far from the aperature of the waveguide are the C Band V & H probes? Maybe I can help.

 

[skysurfer]

my dish's f/D ratio is .36

the inside diameter of the throat is 2 3/8" (smaller than most throat diameters, btw)

the distance from the front edge of the throat to the closest c-band pickup probe is 3 7/8" and 4 5/8" to the c-band pickup probe furthest from the front of the throat.

i have always felt a f/D setting is important because the corotors and cal-amp and the adl feedhorns that I have installed all stress about using the f/D ratio of the dish to set somethign on the feedhorn before the install - usually how far to slide the throat into the scaler ring before tightening down the set screw. I guess GEOSATpro thinks it doesn't matter since there are no markings regarding f/D on their feedhorn/LNB combo.

 

[SatelliteAV]

The F/D is extremely important. Not that we didn't think so, just that the manufacturer didn't!

We have had the CK1 on the roof for several years now and enjoy the convenience of working with the voltage controlled polarity. As I remember that when swapping the LNBF out with the old Corotor, the horn was in a similar F/D position when peaking the BER.

The C1 is well marked ......

 

[Anole]

Could you give us a little PDF we could print and stick on our CK-1's?
. . . and maybe the C2's, for anyone with the good luck to have one. -


Perhaps with a ruler scale off to one side in inches or millimeters, so we could verify we had the right dimensions.
Knowing where to line up the F/D scale with the open end of the LNBf shouldn't be a problem.


edit: also, could you confirm the picture in post #2 of this thread?
It is not in agreement with recent tests by our members.
And if the orientation mark has varied from batch to batch, that's fine - just let us know.

 

[skysurfer]

The F/D is extremely important. Not that we didn't think so, just that the manufacturer didn't!

We have had the CK1 on the roof for several years now and enjoy the convenience of working with the voltage controlled polarity. As I remember that when swapping the LNBF out with the old Corotor, the horn was in a similar F/D position when peaking the BER.

The C1 is well marked ......

Is the C1 a c-band only version of a GEOSATpro feedhorn?

I may spend an hour tomorrow doing a test - I plan to set the throat 1" out from the scaler ring (throat 1" into the dish compared to the scaler ring) and then move the feed in and out at 1/8" increments from 36" to 35" (the published focal length of my dish is 35.75") and note with my signal meter the c-band signal strength at each test point and probably end up using the point that gives me the best result. Ideally, I would like to get instantenous signal strength feedback as I make the adjustments, but working in front of my dish cuts off too much signal to make a live-time measurement as I do the movement.

If I get better instruction in this thread about f/D setting (where to adjust the scaler ring on the throat) or where to measure the focal point to if it's not a typical 1/8" inside the front edge of the thoat, then I'll use that info.

Ku is not required but would be gravy if is anywhere close enough to the focal cloud to work - I see its pickup probes are way to the rear of the feedhorn.

 

[SatelliteAV]

We had requested an F/D scale from the manufacturer, but it was not available for the unit. In my initial sample testing I found that the face of the feedhorn throat was set to similar placement of the removed Corotor. I have samples from 5 different C/K manufacturers and none have a stamped scale..... nothing to go on here, but experimentation and a fine tuning process while adjusting for peak BER.

Personally, in the many years of C-band installation I have not relied on the F/D scale except for a quick reference while guestimating the preassembly. Have always used a meter or spectrum analyzer to peak and never paid much attention to the stamped scale. I can remember many service calls where customers installed the feedhorn to F/D scale specs, but the scaler was in an incorrect position due to incorrect buttonhook or arm installations.

We have noted in previous posts, that while the arrow was specified for manufacturing to be the 12 o'clock (zero skew) it does appear that it actually is 90 degrees out and is the 9pm (horizontal) reference. All units have been identically manufactured and no variance in stock.

Could you give us a little PDF we could print and stick on our CK-1's?
. . . and maybe the C2's, for anyone with the good luck to have one. -


Perhaps with a ruler scale off to one side in inches or millimeters, so we could verify we had the right dimensions.
Knowing where to line up the F/D scale with the open end of the LNBf shouldn't be a problem.


edit: also, could you confirm the picture in post #2 of this thread?
It is not in agreement with recent tests by our members.
And if the orientation mark has varied from batch to batch, that's fine - just let us know.

 

[Anole]

Brian -
Thanks for the info and clarification.
Always a pleasure.

Of course, many of the fellows here are not professional installers nor equipped with the best test instruments.
For us, any reference info is assuring, and may get us in the ballpark, even though it might be misleading.

Some day I'd like to have the pleasure of seeing a pro install a C-band dish, and align it to the last gnat's ... eyebrow.
Should be most illuminating. :up