[ntp:questions] WWVB 60kHz Receiver
John Ackermann N8UR
jra at febo.com
Fri Apr 14 12:28:14 UTC 2006
> I"m trying to build a clock that uses the WWVB signal to keep its own
> time. I have everything built and working except the Antenna portion.
> I have a 1.1mH ferrite rod Antenna.
> I know tuning it would require a capacitor that I calculated to be
> 7700pF. The problem I am having is tuning it. I am not sure how to
> test it to make sure it is working correctly. I have tried
> broadcasting a 60kHz signal from a function generator and viewing it on
> an O-scope and Spectrum Analyzer, but I"m seeing nothing. I"m looking
> for any suggestions to prove I have this tuned correctly.
I don't know of any simple way to tune other than what you're trying
(using a signal generator and receiver). Depending on the Q of the
inductor, the resonance might be very sharp and you may need to tune
quite a distance around 60kHz to find it -- particularly if your signal
generator calibration is questionable. Also, be careful that you don't
load the antenna as you try to couple signal into it.
Another thought -- how are you impedance matching from the antenna to
the receiver? Depending on design, a loop may be a high impedance and
loading it with 50 ohms may not work too well. The shielded loop
antenna I built (http://www.febo.com/time-freq/wwvb/antenna/index.html)
used a 1 turn loop intertwined with the tuned loop to transform the
impedance down to a more usable level.
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