On 4/3/2015 1:08 AM, Jan Panteltje wrote:
AGC (Automatic Gain Correction[1]) will keep that voltage high as long as possible with weakening signals.

Yes, I can hear that work if I hit resonance quick, the volume jumps
up, but then settles back down.



I'll be measuring across a resonant ferrite rod, I don't know what a
minimum usable voltage would be. I'll go check.
Mikek

Depends how far you are from any transmitter, and the direction the ferrite rod is pointing.
For maximum signal it should be like this:

|
| ------- 0 transmitter
|
rod


Yes, the long rod I reference before has a wide null off the ends.
I have listened to two different stations on the same frequency, just by
rotating the rod. I have it on a Lazy Susan.


The thing to watch is the Q factor,
the detector circuit can be seen as a resistor in parallel with the ferrite rod and tuning cap.
----------
|( | |
|( === [ ] Rp
|( | |
---------

The higher Rp, the higher the Q factor, the more signal, the narrower the bandwidth
B = f / Q

Yep, I have an old Booton 260A for measuring Q.
Thanks, Mikek


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