[ntp:questions] WWVB 60kHz Receiver

John Ackermann N8UR jra at febo.com
Fri Apr 14 12:28:14 UTC 2006

bgjim225 wrote:
> 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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