  We have extensively searched for periodic signals from the soft-gamma
repeater SGR 1900+14, at 430 and 1410 MHz with the Arecibo telescope. Our
observations did not reveal the 5.16-s periodicity discovered at X-ray
wavelengths by Hurley et al. (1998). We place pulsed flux-density upper limits
of 150 and 30 uJy at 430 and 1410 MHz respectively. In the course of the 1410
MHz search we discovered a 226-ms radio pulsar, PSR J1907+0918. Its period
derivative implies that the age of J1907+0918 is only 38 kyr, making it one of
the youngest members of the known pulsar population. Independent lines of
evidence in support of this apparent youth are the unusually high degree of
circular polarization and a relatively flat radio spectrum. The close proximity
of this young radio pulsar to the supernova remnant G42.8+0.6 poses a problem
for the proposed association between the G42.8+0.6 and SGR 1900+14.
