Jim Thompson wrote:

On Wed, 21 Jul 2004 21:48:28 +0200, J M Noeding
wrote:


Hi
It seems to be some problem to build equipment to measure over
+35...40dBm IP3, and xtal filters seem to cause intermodulation
problem with this level

What I am after is constructions to build which works to measure
higher IP3. Would also be interested to see IP3 measurements for xtal
filters

73, Jan-Martin
---
J. M. Noeding, LA8AK, N-4623 Kristiansand
http://home.online.no/~la8ak/c.htm


Padded-down spectrum analyser ??

36 to 63V P-P into 50 ohms ain't easy ;-)

...Jim Thompson

IM3 is generally projected up from measurements made at much lower power
levels -- on most RF circuits running at useful power levels the
3rd-order IM products vary as the cube of power, so you measure the
power-in/IM3-out levels at lower input levels and plot it all on a graph.

Not that I can answer the OP's question, and padding down the signal is
probably going to be a featured part of any setup.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com