Choosing a DiSEqC Switch

[first attempter]

I have two dishes at my house, one pointing at Astra with a twin LNB and one pointing at Hotbird with a quad LNB. I have two Fortec Star Beta FTA receivers, one upstairs and one downstairs and each is fed with a PF100 feeder from one of the LNBs on each dish. I manually changeover the feeder on the IF input port of each receiver depending on which sat is required for viewing by that receiver.

I'm considering whether I could put an inexpensive 2 way DiSEqC switch behind each receiver to make the dish selection automatic. My receivers support DiSEqc 1.2 and the options in the antenna setup menu appear to support a 4 input switch (the options are : LNB1, LNB2, LNB3, LNB4, AUTO, OFF, Mini A, Mini B). I assume I would set up for a 2 way switch using LNB1 and LNB2.

There seem to be many versions of switch at different cost around and I'm wondering what the implications of buying too cheap might be, (signal degradation, or other factors?). Also if I installed say a 4 way switch, would that work OK with two of the switch inputs being left open circuit (I'm thinking in terms of any future expansion of my system with this question) . I realize that perhaps the forum does not allow specific product promotion but I would appreciate any general guidance from experts on this question please.

[Robbo]

You just need a couple of basic Diseqc 1.0 or 2.0 switches.

I have bought a few from ebay and southernsatellite, various makes and not had a problem with any of them. Some branded, others not.
You could always grab a spare while you're at it, for if one goes wrong, they are as cheap as chips.

Yes a 4 way diseqc switch can be used, even if you only need a two way. Very easy to setup with the Fortec Beta.

[first attempter]

Thanks Robbo for the info. I've had a quick look on ebay and there are a lot to choose from. I looked at the Product Descriptions of three switches and they each state an Insertion Loss of 3dB. Is that right? I understood that 3dB loss is a halving of the power. Surely that much loss should not be introduced by a switch?

[Robbo]

3dB is not signicant, considering that 10 metres of cable will attenuate by the same amount. As long as your cable run is not excessively long (>30m) the diseqc switch attenuation will not affect you.

[first attempter]

Thanks Robbo for that technical info. So to be sure I've understood, using say, 10 metres of cable from LNB to receiver would reduce the power of the signal leaving the LNB by half and then inserting the switch would then reduce that half power signal again by half, so a quarter of the power of the LNB signal will arrive at the receiver which is still enough to operate OK. Is that right?

[Robbo]

Up to 40m of benchmark quality cable can happily be used for a Sky minidish on 28E.

Which equates to approx 12dB.

Although I am sure that up to 60m can be used as I have tried it.

When dealing with RF and microwave frequencies, you will drive yourself mad using linear units, stick to dB. 3dB is next to nowt!

[first attempter]

Thanks for the info Robbo, I've now bought a pair of Technomate TM-2S 2x1 switches.
Fitted up and worked perfectly on one of my receivers.


But on the other I've either created a problem or its a co-incidental receiver failure. The receiver powers up straight into the menus and I cant get out of this to view anything. I had the receiver power off at the mains when I coupled the switch in. I've disconnected the IF input to the receiver completely and powered off and on again but it still goes straight to the menus. Any experience of this problem?

[Robbo]

Fortec Star Beta receivers are very dubious anyway. I had one once and the software was very iffy, with it often crashing and getting locked up. Connecting a Diseqc switch to it, should not make a receiver go wrong.


If the receiver won't come back by turning it off etc, with everything disconnected, I vaguely remember a procedure where you connect a null-modem serial cable between two receivers and copy the firmware from one to the other. If in guarantee still, get it replaced otherwise.

[first attempter]

Thanks for your reply Robbo. Guarantee long expired.

But I've got it working again now and thought I would add this final post to the thread just in case it might be of benefit to any other novice like me who might experience a similar problem with the Fortec Star Beta Receiver.

I should perhaps have mentioned, that the day before I installed the new switch I had carried out a Power Scan (Blind Search) on both satellites which pulled in a lot more channels. Following this, I had scrolled through the now bigger channel list and I did notice that I had to take my finger off the button to let the machine catch up, but being a bit impatient I tried this rapid scrolling again. It seemed to be jerky and got stuck but I turned it off and forgot about it. Then I installed the switch, powered up (the first time after this rapid scrolling) and it only powered up in the Menus from which I couldn't escape to view anything.

The eventual escape. In desperation, from the System Setup menu I selected the Data Reset sub menu and then Factory Setting and then Delete All Channels. I then setup the new diseqc switch settings in the Antenna setup menu and then I did a satellite scan. It worked and I could view channels again. I then did a Power Scan on both satellites. I am now operating it with more patience so the software doesn't get stuck. Hopefully will be OK now.

So thanks for your help, my original objective is now achieved.

[Robbo]

Ok Good.

Yep I think mine used to do stange locking up things when I asked it to do what it is supposed to, one of the reasons I got rid of it.