C185 pilot reported being notified by ATC of radio malfunctioning.

Narrative

I sent my Garmin 430W out for overhaul and once completed; repositioned my Skywagon from ZZZ1 to ZZZ to install. I then taxied out for takeoff from ZZZ. With unicom tuned; I pressed the squelch to set volume; and broadcast 'ZZZ traffic; Aircraft X holding short Runway XX.' Silence. I then broadcast 'Aircraft X; is anyone in the pattern at ZZZ?'. On a sunny day; it is unusual for ZZZ to be void of traffic; but it happens. I carefully looked down final approach and observed no aircraft so I announced ' ZZZ traffic; Aircraft X; departing Runway XX; intersection departure; Right turn out'. (Runway XX requires right traffic). The transmission gave a normal side tone in the headset. Climbing out I contacted ZZZ1 Tower with the ATIS to obtain class Bravo and landing clearance. Tower frequency was slightly scratchy; but clearly audible.Upon landing; ZZZ; Tower advised of possible pilot deviation and provided a phone number. Unbeknownst to me; my UNICOM transmissions were unheard and my departure caused a C-152 to go-around. Naturally; I am pretty upset by this and I'm on my way to the airport now to investigate/troubleshoot the radio to investigate how this could have happened.