A travelling-wave parametric amplifier has been constructed in the h.f. band with the object of comparing theory and experiment. The signal line is a low-pass filter in which the shunt elements are similar varactor diodes. The pump is coupled into each diode from a high-pass filter pump line.Gain, bandwidth and noise factor have been studied under diverse conditions. These include matched terminations, mismatch at the load and mismatch at both source and load. In the latter case the possibility of regenerative reflections arises. The signal gain is of the order of 10dB, the bandwidth is approximately 3 Mc/s and the double-channel noise factor is less than 1.1 at midband (6.7 Mc/s).