I was using VDR with two DVB cards and a Universal-Twin-LNB. When I decided to buy a third DVB card, I needed also a third connection to the LNB. I didn't want to climb on the roof and replace my Twin-LNB with a LNB with four outputs and I also didn't want to lay another cable, so I looked for a Multiswitch to get a third and maybe a fourth output for VDR. But all the Multiswitches I found, only work together with Quad-LNBs.
I found a very cheap Multiswitch, which is offered under various names and prices, I have seen it from 15 up to more than 50 Euro, so look closely for the best price. You can recognize this switch easily by the blue plastic sides and the way the input and output sockets are arranged (see the picture below).
This switch is able to supply the LNB with the correct voltage to switch the polarization, but it did not forward the 22kHz tone to the vertical input. The reason for this is that the 12V on the vertical input are made with a 78L12 voltage regulator and the 22kHz signal is cut off by a small capacitor.
The idea was to add the 22kHz signal again to the vertical input. With a resistor and a capacitor, this problem can be solved very easily. You have to pull the output pin of the 78L12 out of its hole and solder a 100 Ohm resistor and the minus pin of a 10uF capacitor to it. The other end of the resistor is then soldered in the hole where the pin of the 78L12 originally has been. The plus pin of the 10uF capacitor has to be soldered to another hole at the center of the board, near the 78L12 (see photo).
This little highpass filter forwards the 22kHz signal from the horizontal input also to the vertical input and makes the Multiswitch work perfectly as expected.
This modification will only work if you use the Multiswitch only with VDR or another DVB receiver, but not with old analog receivers.
If you are living in an apartment and you don�t have control over the sat dish, such a Multiswitch can also be the solution for you. All you need are 2 independent cables to the central Multiswitch in your house and connect them to your little Multiswitch.
