Light Transport; Low Wing; 2 Turboprop Eng
Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (yrs) 3
Communication Breakdown
ATC Issue All Types; Airspace Violation All Types; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter CFTT / CFIT
Flight Crew Requested ATC Assistance / Clarification; Flight Crew Returned To Clearance
ATC Equipment / Nav Facility / Buildings; Procedure
Aircraft X was inbound to SNS at 10;000 feet. He was on freq. 127.15 which usually has very good coverage. The pilot checked in at 10;000 and I descended him to 5;000 even though I thought I issued him 7;000. ZOA called me on the landline and reminded me of the MVA. I immediately instructed Aircraft X to maintain 6;400 immediately for the terrain. I issued it to him and second and third time since he wasn't responding. ZOA called again and said Aircraft X went back to their frequency because I was coming in 'broken' on 127.15.I will make sure I issue an altitude to comply with Minimum Vectoring Altitudes (MVA). Another possibility would be for aircraft below 10;000 feet inbound should be on 133.0 frequency; which has better coverage.
NCT Controller reported of having an aircraft inbound to a destination and descending it to an incorrect altitude. Center called and reminded the Controller of the MVA. Reporter tried calling aircraft three times to give it a correct altitude. Aircraft went back to centers frequency because reporter's frequency was coming in broken.