Echo-enabled harmonic generation (EEHG) free electron lasers (FELs) hold great promise in generation of fully coherent radiation in x-ray wavelengths. Here we report the first evidence of high harmonics from the EEHG technique in the realistic scenario where the laser energy modulation is comparable to the beam slice energy spread. In this experiment, coherent radiation at the 7th harmonic of the second seed laser is generated when the energy modulation amplitude is about 2~3 times the slice energy spread. The experiment confirms the underlying physics of EEHG and may have a strong impact on emerging seeded x-ray FELs that are capable of generating laser-like x-rays which will advance many areas of science. Show Partial Abstract