There really should be no problem detecting such large signals with an
unbiased diode. I use Agilent zero-bias Schottky detector diodes, but
your 1N34 should work about as well. The key is realizing that you
simply don't get much output from the diode detector at low input
levels, but I'm quite able to detect signals below 100uV -- yes, 100
microvolts -- with mine. Your signals are actually quite large, and
start to get into a transition region between response at low signal
levels, where the output voltage is proportional to input power level
(into a resistive load), and response at high signal levels, where the
output voltage is proportional to the input voltage. So you may need
to calibrate at several points. Be aware, too, that the response
depends on temperature. I believe you will be able to find some
application notes on the Agilent web site in the components section.

Although there are some really nice RF level detector ICs now from
places like Analog Devices and Linear Technology, a simple passive
diode detector can still be useful in many cases.

Cheers,
Tom