[regenfreak]

Before Christmas, I wrote that I was going to build another 6-gang tuner with an unbalnced dual gate mosfet mixer because I have three of the same military, silver-plated 6-gang air variable capacitors.

The attached schematic is the finished version 2 tuner. The design is very similar to the first version with a BJT mixer except it uses one inductive coupled tunable BPF and one capacitive coupled tunable BPF in the RF amp stages.

Everything performs well as expected. The local oscillator has a buffer amp that drives gate 2 at a much higher signal level than the RF input from gate 1. The transconductance is amplitude modulated by the local oscillator "pump" voltage (see attachment 5). I installed a digital frequency display like the first version. It is getting harder and more expensive to obtain the original vernier tuning dial knob so I have used a cheapo chinese alternative which is over 180 degrees of rotation. It works Ok but not as good as the originals.

My next projects will be the experimentation with a balanced dual gate mosfet mixer which is more difficult to implement.

I consider building a 8-gang varactor tuning FM receiver...I have some ideas floating around but I nowadays spend much more time keeping fit since the start of the year and spend less time on electronic projects.