[Lf] Third Order Intercept Point Measurement

[Frank Gentges K0BRA]

Hi,

I obtained a second HP 606A signal generator last weekend at the Winterfest.
After some repairs it is working and I hope to be able to measure the third
order intercept point of some of this LF gear.  In particular, I would like
to improve on the Berhans active efield probe.  Cliff, K7RR suggested that
they had found the Burhans active antenna preamp could be improved by
adjusting the bias whilst monitoring the second order products.

Dressler <http://www.dressler.com> advertises a high dynamic range active
antenna which goes down in the LF range and has a third order intercept of
+50 dBm.  Not specified is the impedance for this measurement.  The input of
an active antenna amp would be on the order of 1 megohm to reach 40 kHz.  I
suspect they use 50 ohms for their reference here.  If so, that is quite
some performance.  I doubt we can meet that but it makes a nice objective.

Anyone else interested in working with me on this circuit design and testing
project?

Frank Gentges
K0BRA ex AK4R, W3FGL
See www.amrad.org/projects/lf for the latest on LF