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 \mu Jy 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 .