How to Test an LNB with a Multimeter and Satellite Meter

A suspected LNB fault is frustrating: you are up a ladder in the cold, and you need to know whether the box on the arm is actually dead before you climb down to buy a replacement. A few simple tests — with a multimeter and a satellite meter — give you the answer in minutes.

Test 1: Is the Receiver Supplying Voltage?

The LNB is powered over the coax. Disconnect the cable from the receiver, set your multimeter to DC volts, and touch the probes to the centre pin and the outer shell of the receiver's “satellite in” socket. With a channel tuned, you should read 13 V (vertical) or 18 V (horizontal). If you read 0 V, the LNB power setting in the receiver is off, or the receiver is faulty — not the LNB.

Test 2: Is the Voltage Reaching the LNB?

Now measure at the LNB end of the cable. Unplug the cable from the LNB and measure between centre pin and outer. You should see roughly the same 13–18 V. If the voltage has dropped to near zero, the cable has a short or a break.

Test 3: Check for a Short Circuit

Disconnect both ends of the cable. Set the multimeter to resistance (ohms). Measure between the centre pin and the outer braid at the receiver end. You should see an open circuit (infinite resistance). If you see a few ohms, the cable or connector is shorted — braid touching centre pin. This is a very common fault.

Test 4: Does the LNB Draw Current?

A healthy LNB draws around 100–500 mA. With everything connected and a channel tuned, measure the current in series. If the LNB draws nothing at all, it is dead. If it draws far too much (over 800 mA), it is shorted internally — also dead.

Test 5: Signal Meter Test

Plug a satellite meter between the LNB and the receiver. Tune a known channel. If the meter shows signal strength but the receiver shows no quality, the LNB is amplifying but producing a noisy or wrong-frequency output — it is failing, not dead. If the meter shows nothing at all, the LNB is dead.

Interpreting the Results

• Voltage present at LNB, no signal: LNB dead — replace.
• Signal strength low, quality zero: LNB noisy — replace.
• Voltage missing at LNB end: cable fault, not LNB.
• Voltage missing at receiver end: receiver setting.

Safety Note

Never connect a powered LNB cable to a multimeter while also touching the centre pin to ground — you can pop the receiver's LNB supply. Disconnect before probing.

Testing an LNB is a process of elimination, not a single reading. Work from the receiver outward, and you will know exactly which part to replace.