Hi Avery,

Avery Fineman wrote:
One of the most innovative in my estimation was the loop built on an
unused bicycle wheel rim (spokes removed).

Indeed. I saw one of those he http://lakeweb.com/rf/wwvb/ (may or may
not be the same one you found), and it is a clever idea. I'm thinking now I
might build one like that as well as a ferrite rod version to compare with;
since the ferrite will increase the effective area of the antenna by the
square of its effective relative permeability, I want to believe that a 1/2"
ferrite rod can compete with... well... at least an air core loop, uh... the
size of your hand? (I don't have various references here with me to start
looking up the effective relative permeability of a ferrite rod of a given
l/d ratio... hopefully in the ballpark of 20-50...)

I also found that people did occasionally ask about really large diameter
(1") ferrite cores, and while the usual response was that you could, of
course, pack a bunch of smaller rods together to make a big one, apparently
no one has the considerable $$$ around to build, say, a coffee can sized
ferrite core antenna. Would be something to see though! Anyone want to
donate some fat ferrite rods to me? :-)

My own loop is 58 1/2 turns of #14 AWG THHN electrical wire self-
supporting with a mean diameter of 2 feet, 8 inches, then bound with
cheap twine that was well varnished with McCloskey's "Gym-Seal"
floor varnish. The electrostatic shielding was provided by heavy-grade
kitchen aluminum foil (with a gap, of course) that was bound with a
second application of twine, then varnished. Q at resonance is about
44, good enough for about 1.4 KHz BW by itself.

Not bad at all!

Worked out well
and I can't observe any funny spikes from appliances or other
non-WWVB signal things after the FET stage.

That's good to hear; noise seems to be a common concern.

I believe you said your receiver was a synchronous design, correct? I'm
still liking the envelope detector approach, but I've yet to hear about
anyone successfully employing this (simpler) method.

60 KHz signal voltage
across the loop at resonance is estimated at about 90 to 120
microVolts.

I don't suppose you have an estimate of your signal to noise ratio?

Location here is northern Los Angeles in the Verdugo
Hills (a mile of hills between here and Boulder, CO)..

I'm in Corvallis, Oregon, which -- eyeballing it on a map -- is perhaps half
again as far from Boulder. I have one of the inexpensive self-setting
clocks that does work pretty reliably _if keep in certain positions within
my house_. I've read that these also set themselves at night when the SNR
is significantly higher too.

Ferrite/powdered-iron core "antennas" used in consumer market
radio clocks seem to work very well.

I was going to get some of the 1/2"x4" or 7" rods from Ocean State
Electronics he http://www.oselectronics.com/ose_p88.htm ... they also
have some inexpensive pre-wound rods meant for AM radios
(http://www.oselectronics.com/ose_p91.htm), but they're apparently tuned for
the AM broadcast band and therefore I'd have to re-wind the things anyway.

This is hopefully going to end up as a class project and therefore the goal
of learning how to build your own antenna and receiver is the reason I'm not
intending to just go and use someone's "all in one" WWVB receiver IC (even
though colleges seem to push that approach these days... but then _someone_
had to design that IC, right!?).

---Joel Kolstad