Masthead Preamp

The cable to the Cebik Moxon aerial in the attic is RG58 and has a loss of over 3dB so I’m considering putting in a masthead preamp.

The cable loss was measured by sending the AW07A antenna analyser signal at 145.8MHz down it and measuring the RMS voltage at the HP 54615B scope. This was 194mV. The AW07A signal direct to the scope was 292mV. So the voltage loss was 20log \frac{292}{194} = 3.55dB.

However, it’s not just a matter of inserting the preamp into the signal path. It needs powered somehow and protected from transmit RF.

Here’s some scribbles from my lab book showing my initial thoughts on how to do this. I got an M–100 preamp for Xmas so I’ll use that.

Preamp Scribbles
Preamp Scribbles