Air taxi pilot reported a lack of timely communication with ATC while on the initial approach at night in mountainous terrain; resulting in flying below the minimum vectoring altitude. The pilot re-established ATC communications and safely completed the approach and landing.

Narrative

I was on radar vectors towards GABBY intersection at 9000 FT MSL. GABBY is 17 miles east of the TWF VOR on the 78 degree radial and is on the ILS or LOC Runway 16 approach into Twin Falls. Idaho. As I was approaching the localizer for Runway 26; a commercial flight broadcasted that ZLC was looking for me on 118.05 (which I had selected on comm radio #1). I turned up the volume and did a squelch test and called ZLC. ZLC responded to me saying; 'execute an immediate left 180 degree turn;' which I executed and responded to verbally. The commercial flight asked if I had made the turn; to which I responded; 'yes and I'm nearly on the localizer.' ZLC cleared me direct to GABBY and then cleared me for the ILS Runway 26 into TWF. Shortly thereafter the Controller provided a phone number to call for a possible pilot deviation; which I called upon landing. Contributing factors to the occurrence: Lack of currency in this aircraft; an ex-military aircraft with overhead; backwards switches; different from all the other aircraft in the fleet. old style radios where the volume knob is the 3rd stacked knob on top of frequency knobs (KHZ and MHZ). Poor area of radio coverage with ZLC. Single pilot operations; in weather at night with an Autopilot that does not have altitude capture and must be monitored continuously. I'm speaking with the Chief Pilot tomorrow and advising I will no longer fly the aircraft at night and in weather. It's a good day VFR plane. The issue with ATC was that I crossed the threshold of their minimum vectoring altitude fro 9000 FT MSL to 11000 FT MSL; thus the; 'execute an immediate left 180 degree turn; radio transmission. Things that could help to avoid a similar occurrence: Equip the aircraft with similar NAV/COMM avionics as other aircraft in fleet (Garmin 1000). Recurrent/recency of experience flights with company check airmen when out more than 30 days from flying oddball; differently equipped aircraft. Install Autopilot that integrates with updated Garmin avionics suite; with altitude capture. Add a second pilot when flying at night in IMC. Increased vigilance on pilot's part to test squelch feature on every frequency change.