Diseqc Switches / LNBs Mounted Together

[a33]

Forget 97W then. It's not my cup of tea. With 87/91/95, 99/103, 125W using 3 dishes, that's the best of Ku these days.

When you are going for something like 87/91/97 and 95/99/103 and 125, you'd need a diseqc 1.1 switch anyway. No diseqc 1.0 switches + splitter could do that!

(I use a very cheap 8/1 diseqc 1.1 switch from China since recently, stacked with a 4/1 diseqc 1.0 switch. Works perfectly.)

greetz,
A33

 

[cyberham]

Step by step. Step 1 is just to receive 87W, 103W, 125W on 3 separate dishes. After that, we'll see what we can get additional. I will source additional parts from more local if the costs are reasonable.

 

[cyberham]

The GSP Bullet LNBF was made for tightly spaced multi-lnb configurations. Not sold anymore though.

I have two Geosatpro SL-2 bullets. Time to start taping them together since I now have a dish installed on 87W and a second on 103W.

 

[cyberham]

A splitter has two ports on one side, and one port on the other side.
In this case the two ports are connected to ports A and B of the diseqc switch, and the one port is connected to the long cable, to the 'receiver' port of the second switch.

What happens is this:
If the receiver selects diseqc 1.0 port A, port A of the first switch is chosen, and via splitter and cable arrives at 2nd switch and chooses port A of that switch.
If the receiver selects diseqc 1.0 port B, port B of the first switch is chosen, and via splitter and cable arrives at 2nd switch and chooses port B of that switch.

Switching to port A, a switch always does that automatically: it is its default port when it receives a voltage. No diseqc repeat needed.

Switching to port B requires a command repeat in this setup:
First the first switch receives the portB command, and switches to port B.
Now via the splitter and the cable the voltage arrives at switch nr. 2; but that defaults to port A.
After a second port-B command, switch 1 stays in port-B mode, but now switch 2 switches to port B.
QED.

Clearer now?

Greetz,
A33

Just as a follow up, I tried this technique of using two diseqc switches with a splitter in between to allow one long run of cable to reach dishes installed far from the receiver. My situation is different now with one motorized dish at a distance with a linear and a circular LNB, and a fixed dish in a different location with one LNB. The cable path distance from receiver to the motorized dish is about 140 feet.

This technique worked fine eliminating two separate long cable runs to the distant motorized dish. But, the problem was that apparently the voltage was too low as a result of having two switches and a splitter in the long path. The vertical polarization (13V) worked but the horizontal polarization (18V) didn't. So I had to remove extra switch and splitter and simply use one switch for the motorized dish. And a separate run to the fixed dish. Too bad since the solution was elegant.

 

[a33]

This technique worked fine eliminating two separate long cable runs to the distant motorized dish. But, the problem was that apparently the voltage was too low as a result of having two switches and a splitter in the long path. The vertical polarization (13V) worked but the horizontal polarization (18V) didn't. So I had to remove extra switch and splitter and simply use one switch for the motorized dish. And a separate run to the fixed dish. Too bad since the solution was elegant.

That's too bad, that the 18V voltage became too low. The switches, and maybe also the quality of the cable could indeed cause that.
Is the cable made of good quality copper, center and ground braith? Or is it made from higher resistance CCS (copper cladded steel)?

Some other thoughts:

In the switches, it would be the darlington pair transistors that cause the voltage fall.
I read that instead of a darlington pair, you could maybe also use a 'complementary darlington transistor' (sziklay pair, or is it sziklai?), causing only half the tension fall. But you'd need to change the diseqc switches internally for that, and I don't know if it would affect the functionality of the switches.
Never seen a modification like this; but that would not be a reason not to try..? (We should look on the schematics of a diseqc switch first, to check if there would be obvious problems beforehand.)

One other option would be, to use a 18-20 volt power inserter in the distant motor line, which you only switch on when 18V is needed. But I don't know if power inserters always work good; you'd have to check here for experiences by other members maybe.

BTW Some receivers have the ability to use 'increased voltage'; for cases just like these. Your's doesn't have that?

Greetz,
A33

Edit: BTW, which splitter did you use? I hope one without diodes?

 

[cyberham]

Not sure about the RG-6 quality. It is standard single-shield as can be obtained from a local building store. The long run cable loss is probably 12 dB. Good quality RG-11 could reduce that by 5 dB. But sourcing that much RG-11 locally (too expensive to have shipped) is not an option.

As for modifying the switches, that's not on the agenda. Too many other interesting projects in the works to get into component-level experimentation. An external power inserter might be an idea if it could be inserted permanently. But needing to only use it for horizontal tps would be awkward.

My GSP microHD is pretty basic. It doesn't have the capability for the voltage to be adjusted. Not sure of the makeup of the splitter/combiner. It's a garden variety type again available at the local building store. It has power pass-through on both inputs as proven by the fact that it worked on both switch ports.

The workaround is to use my main receiver for my 2-LNB motorized dish. And use my backup receiver for the fixed dish. The fixed dish is not such a long run. So all I need to do is change remote controls and push some buttons to switch between dishes: pretty convenient. No physical changes of cables or connections required.

 

[a33]

Not sure about the RG-6 quality. It is standard single-shield as can be obtained from a local building store. The long run cable loss is probably 12 dB. Good quality RG-11 could reduce that by 5 dB. But sourcing that much RG-11 locally (too expensive to have shipped) is not an option.

Is not so much the dBs, it's more the plain old simple ohm-resistance of the cable for DC-current.


BTW If the first switch was still in the house, at the receiver, you could probably also use a manual A/B switch there. Resistance is virtually zero.

greetz,
A33

 

[cyberham]

...BTW If the first switch was still in the house, at the receiver, you could probably also use a manual A/B switch there. Resistance is virtually zero.

greetz,
A33

Done! I just happen to have a 1:2 F-connector manual switch in my junk box from years ago I've never used. It's installed and I now have whole system working into my one receiver. To switch between dishes I simply press the A/B manual switch by the TV.