The personal website of Scott W Harden

Prototype Radio Receiver Improving Daily

This is the current state of my receiver. Unlike earlier designs this one uses NO VARIABLE CAPACITORS! This helps because (a) it reduces cost, (b) makes it easier to build for anyone (it's hard to hunt down identical variable capacitors), and (c) allows it to be totally voltage controlled so microchip or PC control of frequency becomes trivial. Tuning over the entire 40m band is achieved with 3 LEDs reverse biased acting as varactors (wow!). The knobs are potentiometers. The whole circuit runs on 5v.

Markdown source code last modified on January 18th, 2021
---
title: Prototype Radio Receiver Improving Daily
date: 2011-02-03 23:16:55
tags: amateur radio, old
---

# Prototype Radio Receiver Improving Daily

__This is the current state__ of my receiver. Unlike earlier designs this one uses NO VARIABLE CAPACITORS! This helps because (a) it reduces cost, (b) makes it easier to build for anyone (it's hard to hunt down identical variable capacitors), and (c) allows it to be totally voltage controlled so microchip or PC control of frequency becomes trivial. Tuning over the _entire_ 40m band is achieved with 3 LEDs reverse biased acting as varactors (wow!). The knobs are potentiometers. The whole circuit runs on 5v.

![](https://www.youtube.com/embed/ikBk_HQ48hc)