More fun at the office today…I was sitting at my bench and suddenly noticed that my satellite receiver was no longer locked to our signal. I looked over at my spectrum analyzer and saw that ALL of the signals normally present from our satellite dish were gone! Apparently we had lost both our uplink AND our downlink. Very strange…

I called several of our stations and verified that there was no audio anywhere in the network and that we were in fact off the air around the entire state. Here we go again…

I immediately started troubleshooting the problem. I measured the voltages at the upconverter mounted on the dish. The receive cable showed voltage coming from the indoor unit located in the shop but there was nothing present on the transmit cable.

The uplink is down!

Checking the transmit and receive cables with an ohmmeter revealed a partial short on the transmit cable. For some reason swapping the two cables allowed signal and voltage to pass across both cables. I suspect this is because of the different voltages and frequencies carried on the two cables. The transmit cable carries a 70 MHZ IF signal and a 10 MHZ reference for the upconverter. It normally measures about 5 volts DC at the upconverter. The receive cable carries 14 volts DC to power the upconverter and LNB. It also carries the 1 GHZ L-Band receive signal from the LNB.

Although I had the appropriate voltages at the upconverter after swapping the cables there was still no receive signal down in the shop. Initially I thought the upconverter was faulty but swapping the upconverter did not fix the problem. Apparently there was no voltage getting to the LNB from the upconverter. Finally, I swapped out the cable between the upconverter and the LNB and suddenly everything was working again.

Working again…For now…

After 3 hours worth of troubleshooting the network was finally back on the air. Nothing like MULTIPLE problems occuring simultaneously to cause some serious head scratching…