Convert SatelliteAV Ku PLL LNBF to LNB !

[Anole]

Several months ago, I posted to the thread for this device, some thoughts about converting it an actual LNB.
Maybe my comments were buried, as they didn't generate a lot of interest.

Brian of SatelliteAV was kind enough to supply some LNBFs to experiment with.
After a number of setbacks, and lighting a fire under my machinist, we are moving forward.

Here's part of what I wrote. It shows what I was thinking:

1). ... it might be possible to machine off the rings of the scalar, and bolt to the remaining flat disc/rim. That might work to put the LNB on a Primestar feedhorn!
Could also mount the PLL LNB to recycled DishNet oval feeds for use on elliptical dishes.
Or, on DirectWay feed for their dish.
Eg: Primestar 84e, Prodelin 1.0 meter, etc.


I am usually looking for multi-receiver solutions, so one-output LNBFs don't generally draw my attention.
But for 80-90% of users who are using a single receiver, this brings a Standard PLL LNB to their unique feedhorn/dish combo.


2). ... actually, it was a desire to find a PLL solution for the orthomode feed , that got me here:
If an existing & inexpensive PLL Ku LNB could be adapted, would that result in more than just bragging rights?

What do you think about the idea?
Any input on how to do it? I have some thoughts, but you might have a better one.
Where would you want to use a Ku PLL LNB?
:up

 

[toucan-man]

I cant wait to see the test results.

 

[Magic Static]

Cut open the back of a C1 LNBF and mount it on there and make a "741" C/Ku with a great Ku LNB. Just thinking.. Ever pulled the Ku LNB off one of those 741 LNBFs. World's tiniest Prime Focus LNBF under that plastic cap.

 

[tekjunkie02]

An LNB needs to receive the signal from somewhere so it can convert and amplify it, right? That's the function of the "F", it's the feed that focuses the signal onto an antenna that supplies it to the LNB. It's just a matter of physical configuration, so you should(theoretically) be able to find the connection point on the circuit board of the LNBF, and wire in to that point from your remote feed and antenna. Now, as far as the electronic engineering involved in figuring signal gains, losses, VSWR, etc, etc.... well, If i were doing it, would be completely trial and error-repeat until it either works or it doesn't
All of the above is just my humble opinion and comments to add to the discussion. I don't profess to have enough knowledge in this area to give any actual advice, so take it FWIW.

 

[Bongu]

To answer the question posed by the OP, I would love to see one of these able to bolt up to a C-120 flange feedhorn or one of the Prodelin feedhorns used on the 1.8M offset dishes. I do believe the hole spacing is slightly different, so a configuration for each type would make 99% of us happy. If you wanted to mate it up with a WR-75 fitting, this would be the solution for an ortho feed. Cheap PLL on an ortho would rock.

 

[Anole]

Yes. Exactly! Glad to find others on the same page. :up

Here's more of what I'd been thinking...

The scalar rings would need to be machined off.
Then, the round PLL LNB port would need to be mated to the standard rectangular port on an ortho feed.
You find those adaptres on Andrew/ChannelMaster/Primestar/Musak/Prodelin dishes between their feedhorn/scalar and a stock Ku LNB.
That configuration is for when a single polarity is sufficient.
The adapter is the wr-75 c-120 wave guide.
I don't have any; if anyone has a couple they could spare (normally pretty useless) I would appreciate.


Using two Standard PLL LNBs on an ortho would require a multiswitch, as always.
There might be several ways to go about this.
If done right, no switch mods would be needed.
But if the multiswitch had been altered to put out 18v on both inputs, rotating one of the PLL LNBs should fix that.
Might even be a better idea, if voltage drop on long coax was a consideration.

 

[KE4EST]

That should be your best bet anole. Looking forward to seeing what you come up with!

 

[Anole]

I want to use on an Ortho (with those rectangular ports).
As you know, the SatelliteAV Ku PLL LNB will have a round port.
The adapter is used to connect the two together.

If done right, no switch mods would be needed.
But if the multiswitch had been altered to put out 18v on both inputs, rotating one of the PLL LNBs should fix that.
Might even be a better idea, if voltage drop on long coax was a consideration.

I don't actually have any of the adapters, but...
closer inspection of the hole pattern makes it look an unlikely possibility.

Need the adapter to confirm.
Can anyone point me to a source, or send one you're not using?
They come on single polarity dishes such as Musak, and have little use.
Need two to test on an ortho, but even one would be helpful.
.

 

[Bongu]

I would recommend you stick with focusing on one type to get results relatively quickly. Most Ortho feeds for Ku are WR-75 Flange mounts. (the two $20 ones i got off that ebay seller are like this with a TRF and a 90 degree elbow on each)

The adapter would need to be no more than 3 to 4 inches in length and the transition from round to rectangular would need to be almost mirror smooth to avoid signal loss and resonance. Just in case you are wondering, I pulled the 3 to 4 inch measurement from the length of the typical TRF (Transmit Reject Filter) that is usually found on the Ortho feed receive LNBs. I am sure the TRF introduces some signal loss, but it is not a major concern IMHO. The TRF and the 90 degree elbow both have 2 WR-75 flanges on them and they can be machined off pretty easily. This is where I would start if I were tackling this.

The rest of your ideas on functionality are good. I would definitely power 2 such LNBs with 18V and feed them to a modded multiswitch for more distribution options.

 

[Anole]

early PLL pictures

Many thanks those who gave me early pictures of the LNBF without its plastic shell.
That was necessary to formulate a plan on making it into an LNB.
Attached, are a couple of pictures of my own.

In some LNBFs, the scalar has a flat back, and you can just machine off the rings, drill holes in the remaining disc, and bolt it on.
That is true of the prime focus LNBF from SatAV, (the SL1P, as shown by another SatGuys mamber), but may not be so of more traditional parts.

The SL1PLL feedhorn, has a cone shaped back side.
That meant taking off the entire feed, leaving only the "pipe".

As you can see, the "neck" or pipe between electronics proper, and the feedhorn, is very short.
That killed my first idea: threading the neck, as was done by another clever member.

 

[primestar31]

Well, I'd think you first need to pop a hole in the end-cap, and find out where the actual antenna is located, before you can decide a reasonable plan for what to do next to modify it.

Then remember it's a waveguide.....

 

[gabshere]

I want to use on an Ortho (with those rectangular ports).
As you know, the SatelliteAV Ku PLL LNB will have a round port.
The adapter is used to connect the two together.


I don't actually have any of the adapters, but...
closer inspection of the hole pattern makes it look an unlikely possibility.

Need the adapter to confirm.
Can anyone point me to a source, or send one you're not using?
They come on single polarity dishes such as Musak, and have little use.
Need two to test on an ortho, but even one would be helpful.
.

whats it look like maybe i have 1, i will post pic of what i have one is a ku feedhorn it has adapter built in other is a ku adapter

 

[Anole]

...other is a ku adapter

Wow, yes! Those two pix on the right are exactly what I need.
First rate pictures, too. Shows detail I never knew.

As I've mentioned, those show up on dishes for single polarity services like Musak.
Under the shroud, behind the feedhorn (which has round port), is a standard Ku LNB with the traditional rectangular port.
(and the adapter in between)
Most people put the LNB on the shelf, and mount something that'll get both polarities, instead.
The adapter plate is unused.

 

[KE4EST]

Send it to him so we can see the results!!!

 

[Magic Static]

I'll have to visit my junkyard and see if I can find any of those

 

[gabshere]

Anole. You can have this adapter. Just pm me your info. , I'm in Baltimore. So I will have my wife send it to you.

 

[SatelliteAV]

Various C120 to WR120 adapters:

http://www.all4sat.com/swedish-microwave-smw-quarterwave-transformer.html

 

[Tron]

Great link, Brian! Lots of good info on flange types (check out the .PDF) ...

 

[Pixl]

In some LNBFs, the scalar has a flat back, and you can just machine off the rings, drill holes in the remaining disc, and bolt it on.
That is true of the prime focus LNBF from SatAV, (the SL1P, as shown by another SatGuys mamber), but may not be so of more traditional parts.

Here is a picture I posted some time ago where I cut just the nose off a SL1P, left the rings in place. I then drilled and taped holes in between the rings and it bolted up to a C-120 PrimeStar feed horn. It performs quite well.

 

[Anole]

Pixl -

Yes, your earlier work inspired me.
There are also a number of feedhorn recycling threads by others that made me think, too!

Been reading the forum for a few years now (!), and really prefer the technical threads.
Those on Feedhorns, LNBs, switches, motors, and angles are the best.

I'll try to post more about this on-going project (many pictures) but this is the F1 race weekend.