All other transistors are germanium PNP types, mostly 2N993s. Selectivity is provided by three Clevite TF-01A ceramic transfilters and a Collins 2.1 kHz mechanical filter. An extra crystal sharpens up the mechanical filter response for CW use. The design incorporates a true impulse-type noise blanker, with adjustable threshold. Despite its compact size, the DR-30 is relatively easy to service.
Circuit boards slide out from the rear.
The bandswitch and r.f. The P-channel enhancment FET is the only socketed transistor in the receiver. I'm smiling because I just finished the final alignment of my DR-30. The VFO is rock-stable, and dial calibration tracks to within 2 kHz over the full 500 kHz range. As might be expected, the receiver is somewhat suspectible to front-end overload, a consequence partly of unusally high RF stage gain and the fact that AGC voltage is applied only to the IF amplifiers.