First Mixer and Amplifier Picture

The First Mixer features an IR emitter (mounted high right behind the middle transformer) that sends an IR signal to the First VFO Amplifier that controls the gain of the amplifier to keep the output of the VFO section constant to within a couple of dB from 40 to 10 meters.

The Mixer/Amplifier combination features about 14dB of gain while providing nearly 100dB of dynamic range. The sensitivity and dynamic range can be varied by the level of injection from the VFO strip. Increased sensitivity lowers dynamic range and higher dynamic range lowers sensitivity. A good setting is 4 volts P-P VFO injection level. Higher injection levels increase sensitivity.

The injection level is set by the small 500K trim pot at the First VFO Amplifier tied into the Gate 2 ciruit of the MOSFET.

Picture below illustrates how a short can happen with soldering the coils into the footprint. Take a close look at the coil on the left and see the shorted wires. Please double check your soldering when installing the coils.

Please look carefully at the connections on the left hand ferrite coil, the turns are shorted! Please watch out for this when you mount the ferrite coils!

This PCB is from the first run of boards. The board you are using is Rev 2 and is slightly different from the one shown above.