C band reception woes

[FaT Air]

All TP's on 99W are strong here. If I knew I was aimed at a sat, I think I'd bypass the switch, run the receiver direct to one lnb. (use a RG splice to bypass the switch) Do a blind scan. should get the same TP's appearing on H and V polarity only if the lnb operates well on 13v. If all it sees (good Q) is H TP's, you can bet the lnb doesn't like 13v. I would then move that lnb to the other port on the feed, and repeat. (after deleting TP info from first scan to minimize any confusion) Then repeat the above with the other lnb. If a scan doesnt see any TP;s, I'd suspect something with the feed. And here I would rotate the feed 90 degrees, and repeat, to determine if one feed port is truely funky.

 

[Beano_face]

the lnb needs 18 volts... thats why you have no sig quality on H...

lnbf's switch between 13/ 18 volts to change beween H and V

lnb's (H or V) require 18 volts...

 

[rrob311]

OK, I just found out this is a 13 foot dish! The focal length I calculated is about 11 inches past the face of the scalar ring. This dual lnb block that bolts to the motor/scalar looks like a foot extension or so. Does the distance of the LNB to the scalar ring matter? Or is it just the depth of the scalar? The scalar depth is not adjustable. I could take the extension off of the feed and bring the LNB in substantially. The side LNB never has worked very well. The one on the opposite end of the scalar ring has always worked better for H and V. I have had it set to V for months. What other calculations do I need to make? I am going to try and put my Chaparral LNB on the end of it and see what happens. I am not sure if I can setup the skew control tonight because I need to make a cable.

 

[rrob311]

Well I just tried out the Chaparral LNB on the Vertical end and my transponder numbers went back to their normal places. However this LNB doesn't pickup as much as the DMX. So I still have poor reception. I am able to pickup the Mytv feeds on Horizontal pretty consistently. That is it on the side mount LNB. On the Vertical with the current skew fine tuned I can get LWN, ABC HD feeds, and Mytv. It has been like this for months. I can't tell if the trees are blocking the line of sight. I am going to check that now with my gf's new Tablet. I am going to try to hookup the Pansat to the skew control so I can switch the skew from inside the house. I am able to get the Lesea feeds with the lnb opposite the scalar only. With the 13 foot dish I would think I should be able to get the PR mux.(which is my main goal at this point.) If I pull out the side lnb portion of the assembly I could potentially move the LNB 1 foot towards the scalar. This dish was used for uplinks according to the previous owner. I am merely trying to find as many channels as possible.

 

[FaT Air]

move the LNB 1 foot towards the scalar.

post some pictures please, I'm not understanding. Then the measurements from the bottom dead center of the dish to the feed throat, and what you calculated. and the numbers used to calculate it. Somethings gotta be way off.

 

[rrob311]

OK. I took out the extension tube that housed the side LNB and bolted my good LNB back in. All of the V transponder channels that I got before are now locked at a max 85% quality on the Openbox and they don't fluctuate at all!!!!!!! I am also now instantly blind scanning in GDMX feeds which I NEVER had before and the Pentagon Channel. I am going to setup Skew control later so I can switch to Horizontal. I am confident I will be able to get everything on the H side. I measured the Focal depth at the pin or near the Base of the LNB now. Before it was about 10 inches further out. I am not sure if that was the issue but that is the only depth adjustment I could find was taking out the other lnb tube.

 

[rrob311]

I just went out and manually set the Skew to H and I pretty much got everything I have been missing at just about max quality. So that solves the mystery of the portable dish. Too bad I didn't have the manual to figure this out earlier. PS max quality on the S9 is 85% for me.

 

[FaT Air]

The more accurate place to place your calculated focal length is from the bottom center of the dish ta a point approximately 1//4 inch inside the throat of the feed. Not to the probes.

 

[FaT Air]

I got a feelin". Which lnb works, the one on the rear of the feed, or the one on the end of the wave guide out the side? I have a feeling that part with the round flange on the back that the rear lnb mounts to is not wave guide. (Hollow) got a feeling it may be a filter or circulator. Meant to accept a BUC. ie transmitter. That would explain the weak or no signal.

 

[rrob311]

I got a feelin". Which lnb works, the one on the rear of the feed, or the one on the end of the wave guide out the side? I have a feeling that part with the round flange on the back that the rear lnb mounts to is not wave guide. (Hollow) got a feeling it may be a filter or circulator. Meant to accept a BUC. ie transmitter. That would explain the weak or no signal.

The one at the rear of the feed was working better. The one on the end of the waveguide? worked only for super strong signals. That makes sense because the guy I bought it from said he used it for uplinks. I took the waveguide out and bolted the round piece directly to the scalar/rotator gear and I now get EVERY FTA channel known to every list I have had time to check. The center piece (waveguide)? with the side LNB has a piece inside that cuts the sections into 2. I wish I could find a manual so I could better understand all of this. I haven't been able to find out who made this dish. I am able to receive all of the Mexican local news stations with the 1562 sr's. If anyone knows of the weakest channel on g16 let me know and I will see if I can get it. I got 100% of the ones that are on the lists so I am confident that was most of the problem. This dish did come with a Ku Feed assembly but I am not sure where to find lnbs that bolt to the smaller flat flange.

 

[FaT Air]

I Thinks it's figured out. I'd be interested in pics of the part with the piece inside that cuts the sections into 2, So now you only have one lnb mounted, and rotate the feed for the other polarity??

 

[rrob311]

Ya I just rotate the feed with the motor control that I have using the one LNB. The other DMX211 I took off has a drift of about +200 on the transponders so I took it out. The dish is going to be parked at 99 until I can at least get my 6 footer set up. I will try to take pictures of the thing I took off and the other adapters that came with the Ku setup and hopefully someone can shed more light on this since I can't find a manual.

 

[rrob311]

OK this is a little late but I am slow. I am posting pictures of this device I took off that was causing my reception problems. I now get every feed known on 99w so the problem is solved. However I do not know what these pieces are for.

 

[rrob311]

pics

This is the piece I took out that I had both lnb's mounted in.

 

[FaT Air]

Probably a rejection filter. Since it was used as an uplink, the Transmit is on one polarity, the receive on the other. Although there's probably 20+ db isolation, being on different polarities, additional isolation is needed so the transmit doesn't interfere with the receive.

 

[rrob311]

OK that makes some sense. So I have no use for it.

 

[Cham]

Just fyi... the old LNB with the larger connector is actually an LNA; these were one of the first consumer satellite systems where the LNA receives the C-band signal and amplifies it, a down converter in the line changed the c-band to L-band for the analog receiver. The larger connector is an N connector very common in microwave and UHF RF applications. You did the best thing to replace the LNA with a newer LNB.
-C.

 

[gardenman2002]

rrob311,

I had a similar problem with my 741 lnbf and only the vertical can in on mine. put it on both the 6 and 10 footer that was locked in to the same sat and received the same results. replaced and it fixed it. You may need to check the local oscilator frequency in your settings, also check your skew. I have experienced a loss of some vertical channels when the polarity is off. hope this helps. Remember there are alot of gurus here to help. I know ,since i asked some of them myself.
happy channel hunting