The front end synthesizer generates the reference signals used
to convert the receiver output from RF to IF. The lock points are at
(
500) 
100 MHz, where n is an integer. The
synthesizer output frequency is between 2.1 and 15.9 GHz. There are 3
such synthesizers, each of which is locked to the maser. One
synthesizer is used for most wavelengths, but two are used at 1 cm, at
7 mm, and for the wide band mode at 4 cm described in
Section 5.10.