Diode Ring Mixer

40m band is poor today and I want to listen to the AM broadcast band. However, my IC-M700TY HF transceiver can only go down to 2MHz.  Upon checking  my junk box, I found the right components to assemble an up converter so that I can still hear AM broadcasts on my transceiver.

The illustration above depicts a diode ring mixer, In my prototype, I am utilizing four closely matched 1N4148 diodes based on their forward voltage and a pair of  FT37-43 toroids as a core for my broadband transformer. The transformer is wound with four trifilar turns of #22 AWG insulated wire.

After completing the diode ring mixer, I constructed a 10MHz crystal oscillator using the circuit mentioned earlier. The oscillator is producing 2.8V peak-to-peak of 10MHz signal which I believe is well within the requirements for the diode ring mixer. The 10MHz signal will be fed into the VFO port of the ring mixer.

I've enclosed the finished prototype in a plastic container and I've installed a pair of connectors on the side for easy connection of the aerial antenna and the patch cable leading to the antenna connector of my IC-M700TY. The aerial antenna will be connected to the RF port while the baseband output signal can be extracted from the IF port of the ring mixer.

To make this set-up operational, the AM broadcast frequencies will be present at both (10MHz + AM band) and at (10MHz - AM band). For instance, if DZMM is broadcasting at 630KHz, it can be received either at 10.630MHz or at 9.370MHz   ---73 de du1vss