Harmonic generation

During tests with a few 2 meter transceivers I found a problem.
All those transceives seem to have a bad suppression of harmonics .That can not be true.

It seems the tuner itself creates those harmonics when a strong signal is applied
I allready build an attenuator that reduces the RF out of a transmitter to a level the analyzer can handle.
I tried reducing the signal levels by increasing the attenuation.
That did not work.Signal levels did not change. Some RF probably leaks through the attenuator.The problem is not radiation picked up by the analyzer itself. When signal cable is disconnected no signals are visible.

I bought a better attenuator on Ebay. It has not arrived yet.