Fred McKenzie wrote:

Tobin Fricke wrote:

As a project to learn more about building radio receivers, I'd like to
build a WWV receiver (or maybe a receiver for the Canadian station CHU,
since it's nearby and the format sounds easier to decode). I'm looking
for suggestions for how to design such a radio, reading material, etc.

I was thinking it might be easier to design a fixed-frequency receiver
(rather than a tunable one) because I could just select the L and C in the
resonant circuit to give the right frequency. Or, since WWV is at such
"round number" frequencies, maybe I could somehow use a crystal
oscillator?

Tobin-

A couple other ideas:

1. Try your hand at building a crystal set! Just an antenna, a tuned
circuit, a diode and earphones. There could be more sophistication such
as using an amplified speaker and higher-Q tuned circuits.

2. Try a direct-conversion receiver. It may be just a more sophisticated
crystal set with RF preamplifier and on-frequency crystal filter. A
product detector could be included to convert to audio, but a diode
detector should work and wouldn't change the audio tone frequencies.

I considered using this direct-conversion approach to obtain an accurate
10 MHz signal. I wanted to use it to synchronize my oscilloscope so I
could adjust a counter's timebase (or vice-versa). However, I never built
it after finding a Rubidium controlled oscillator on eBay.

Fred

I know that there are several plans on the internet for building a radio
controlled clock. These involve building a fixed frequency rx and then
hooking it up to a clock. How feasible would it be to hook the same
circuit up to an amp and speaker instead of a clock? I suspect that the
clock radios listen in on 60khz, but it should be simple to insert a
crystal or change it to get 10Mhz. Also, you could build a radio with
three frequencies-5Mhz, 10Mhz, and 15Mhz in order to take advantage of
day vs night propagation.