The Cascode 7 Supplemental Page
What follows are a few of the outcast schematics and photos created or taken over the past 4 months of experimenting with superhet receivers. These schematics are presented for experimentation and idea purposes only.
Above. One of the great lessons from EMRFD is to use notebooks for recording experiments, schematics, thoughts and mistakes. I formerly used scraps of paper which invariably would get lost or misplaced. Elementary school scribblers work great.
Shown in Schematic 1 above and below are 2 variations of the receiver front end. These have no 10K shunt resistor and an output link on the mixer tank.
Below is another version of schematic 1. The double tuned filter is designed to be terminated with a 500 ohm output impedance. This is provided by the BJT RF preamp which uses feedback and a 500 ohm -6 dB pad to help define the input impedance and set the amps output impedance. It was a bit noisy but worked okay.
Below in Schematic 2 is a BJT product detector with audio transformer and the actual rig with this product detector in the bottom left portion of the receiver.
One of the many BJT-based IF amps tried during the superhet experiments. The filters are matched with 225 ohms resistive pads.
Below is an actual very ugly version of one of these BJT IF systems and to the right is a sharp photo of the BJT IF System during testing.
Shown below is the VFO copper board under development. The islands were cut with a hobby motor tool. The cuts were performed outside with ear and eye protection and a respirator. Avoid inhaling the airborne particles from grinding. Also shown to the below right, is a photo of an experimental singly balanced common gate mixer. It had prohibitive insertion loss and stability problems and was set aside.
