A TRACON Controller reported they lost communications in their sector and could not communicate with aircraft in time to prevent a NMAC.

Narrative

Working east departure; arrivals; satellite; and final sectors. Traffic was fairly light; but a slight bit of complexity due to weather in the final box to TPA. Aircraft X was a departure from ZZZ on vector and already transferred communications to ZJX. Aircraft X subsequently checked on with ZJX; but was transmitting on my frequency. I attempted to correct what I assumed to be the pilots mistake; but they continued to repeat the check-in. At this point; as I continued to work my other traffic; I could audibly hear the degradation of the frequency and faintly heard other pilots confirm the same. This is when I realized the frequency was dying as it has numerous times in the past; most notably a couple days earlier when another controller had to contend with a similarly harrowing situation. Please review that report for added context of the dangers of our facility equipment.I attempted standby frequencies to no avail. I used guard to try to switch everyone to another frequency; and I asked Aircraft Y flight to return to the broken frequency and blanket broadcast for everyone to switch to the new frequency. At this point; Aircraft X and Aircraft Z; a TPA departure; were on a collision course at the same altitude. I asked the other sector if they still had communications with Aircraft Z; they said no. I called ZJX to have them turn Aircraft Z; but they said the frequency they were on had a stuck mic and they were unable to communicate with the aircraft. I frantically attempted to reach Aircraft X to issue a turn. On my third attempt; Aircraft X responded and turned to avoid the collision/TCAS RA. Suggestion: If we could somehow acquire equipment that worked reliably; particularly frequencies; that would really assist in the success of separating aircraft.