I am trying to experiment with WWVB receiver design...
The antenna I am using is from another WWVB receiver module. It is a loop antenna with a capacitor that I assume is tuned to 60kHz.
Questions-
When I a probe the antenna with the Oscilloscope I don't see the ON/OFF 60k signal I expect. It looks more like a bunch of noise.
When I connect the antenna to an emitter follower it changes the signal. Could the decoupling capacitor be effecting the antenna's tuned frequency?
The 60 kHz signal from WWVB is very weak over most areas of the country, so it isn't surprising that putting an oscilloscope across the antenna doesn't show anything. We're talking about a microvolt-level signal here, and your scope can probably only show signals down to tens of millivolts or so, about 3-4 orders of magnitude too large. You need a lot of selectivity and a lot of gain to pull a usable signal out of the noise and interference.
An emitter follower would not be my first choice as the first gain stage connected to a high-impedance antenna. You need to carefully match source and load impedances here, and take into account the detuning effect that the connection will have. Either the first gain stage needs to have a very high input impedance, or you need to create a lower-impedance tap (or auxiliary winding) on the antenna coil to drive the amplifier.
