Abstract: An airborne weather radar system having a capability of compensating for variable Doppler shift caused by the forward motion of the aircraft and the relative motion of the antenna sweep which includes a local oscillator having a single low phase noise crystal which is operated in its fundamental mode at a predetermined frequency for increasing the pullability away from the tuned frequency of the local oscillator.

Abstract: An improved circuit board having a variety of electronic components mounted thereon and having disposed to the autumn side of the circuit board a backing plate having a variety of thicknesses wherein a thicker portion of the backing plate is disposed near portions of the circuit board or components on the circuit board which are of a higher heat generating nature, said circuit board further having a slot extending through the circuit board and inserted in the slot is a metallic shielding cover which contacts the backing plate. Also disclosed is a method for manufacturing the circuit board.