I have finished the beverage antenna preamplifier. The 9:1 transformer is based on the W8JI’s recommodations. It is wound on the tree binocular ferrite cores BN73-202. I was wondering how the SWR is. When terminated with 450 ohms there is no significiant return power, when terminated with 470 ohms the SWR rise to 1:1,1. Perfect!

The schematic diagram of preamplifier looks very simple – two LC circuits and MMIC. There is much more to do with adjusting bandpass filter and fiting the circuit in the shielted box and all in the waterproof box.

The circuit was later improved with a LED diode which is indicating if the current is flowing to the box or not. Output plug is standard PL.

Tags: preamplifier | beverage | antenna | ferrite cores | transformer | W8JI | schematic diagram

The beverage antenna project for 80m has begun. This weekend I have build simple preamplifier with MSA monolithic microwave integrated circuit. The gain is around 8db and amplifier compression -1dB is at 19dBm point. The gain should be not greater due overloading receiver. Yesterday I have measured input bandpass filter which I got from my another project - RX for 80m. Due the possibility of detuning in various temperatures I have set greater bandwidth. The passband is now 3,52 - 3,92MHz.

Not easy to found non-inductive resistors for beverage. It's terminating resistor with value around 450 Ohms. After several minutes I found suitable resistor in my box. Today I would like to wind transformer 1:9 and move filter on new PCB.

Later I will buy two waterproof plastic boxes and fit all inside them. Probably on the end of November I try beverage antenna on the Air.

Tags: beverage antenna | preamplifier | bandpass filter | terminating resistor