How to build a high performance WWVB receiver front end using jellybean parts

[kf4hcw]

https://twitter.com/codedweller/status/638824875340132352
https://twitter.com/codedweller/status/638816442339594240
https://twitter.com/codedweller/status/638817211377807360

Anyone care to check my work?

The antenna is built from 10 loops of stranded, shielded "security wire"
from Home Depot. It's a 30cm diameter loop, wired to make a total of 20
turns. Remember not to connect the shield (I forgot, and it drove me
crazy for a day! Hate that...). It's designed to be a trade-off between
performance and convenience. It's small enough to toss in a bag, and
good enough to see WWVB all hours without much trouble (my experience so
far anyway). The receiver will certainly take a better antenna if you
like, or even a worse antenna while still doing a reasonable job.

Making the antenna was easy:

* Lay a metric ruler on the desk. Generally these run from 0 - 30cm so
it's just about perfect.
* Lay out the first loop of cable with a handful left over for
connections. Make it as perfect a circle as possible.
* Lay out the next winding by pulling fresh cable along the existing
loop through your hand tightly.
* Perfect the circle, check it against the ruler, and bind it with vinyl
tape... leave the tape on the loop to catch the next one.
* Repeat until you have 10 total.
* Bind up the rest of the loops to keep them neat.
* Strip off the insulation and discard the shield and drain wires.
* Connect the red lead from one end to the black lead from the other -
this makes 10 turns into 20.
* The remaining leads are the connection to your new antenna.

The 48uH coil is a common part used in switch-mode power supplies.
Easily available online.

My results were achieved with the antenna laying on my bench in the lab
half under ground, so most folks should be able to duplicate them.

Next steps are:

* DDS breakout board with 16MHz time base to produce a clean, precise
59KHz LO.
* 8 pin DIP high quality analog multiplier to use as a mixer.
* Some op-amps to select and clean up the 1KHz result.
* Arduino mini/micro to control the whole thing, collect data, and talk
to your computer or smart phone via USB.
* Firmware, software, apps, hacks, etc.

The Arduino will do A-D for the 1KHz, AGC & Frequency control, IO for
the computer via USB, data logging, etc. Normally I would go straight to
an attiny or something like that, but the goal of this project is to
make something that anybody could stretch to make and the Arduino is
about the most popular off-the-shelf gadget out there with all of the
needed pieces so it was a natural choice.

Eventually I'll write all of this up and post how-to's on my blog (I
know, I never get to that stuff...) but I wanted to get this part of it
out there in the mean time.

Comments?

Best,
_M

-- 
kf4hcw
Pete McNeil
lifeatwarp9.com/kf4hcw