so this has been a frustrating few weeks. we had a pretty nasty storm roll through and i had everything unplugged or at least i thought i did, the coax was disconnected but apparently the power supply was still tied in and something came through the AC line i guess. the 7300 powers on, the display lights up and i can even get into the menus, but there's zero receive. like completely dead silent, no noise floor at all, nothing. transmit seems to work based on the power output meter moving when i key up but i honestly havent verified that with anything external yet.

ive been poking around and the first thing i checked was the preamp and attenuator settings, all normal. tried resetting to factory defaults, no change. the antenna connector looks fine physically. im starting to wonder if one of the frontend protection diodes got cooked and is now shorted across the rx path. anyone dealt with something like this on an icom or similar SDR-based rig? i dont have a full service manual yet but im trying to narrow it down before i decide whether to send it to a shop or try to fix it myself.

yeah that symptom pattern — tx working but rx completely dead — is pretty classic for a blown front end. on most modern rigs there's a PIN diode or a set of schottky protection diodes right at the antenna port that are supposed to clamp transients, but a big enough surge just sacrifices them and sometimes takes out the first LNA stage too. the 7300 uses a fairly integrated RF front end so if the LNA MMIC got hit you might be looking at a board-level component that's not easy to source or rework without proper gear.

i'd start by checking continuity and resistance at the antenna port to ground on both center and shield with the radio off and unplugged, just to see if anything obvious is shorted. also worth pulling the top cover and looking for any visible burn marks near the antenna input circuitry. icom's service centers can sometimes just swap the RF unit board but that's not cheap. if you're handy with SMD work and can get the service manual it might be worth a shot yourself, but honestly for a 7300 the repair cost vs. just getting it serviced professionally is probably worth thinking about.

had something similar happen to a friends ft-991 after a storm, turned out to be one of those protection diodes shorted right to ground and killing receive entirely. they actually found it just by measuring across the antenna input with a DMM and seeing basically 0 ohms where there should have been a much higher resistance. ended up being a two dollar part but took like two hours to find it on the board because the schematic they had was a partial copy someone scanned badly.

one thing id also check is whether the AGC circuit is doing something weird — ive seen cases where something in the AGC path fails and clamps the gain all the way down so it looks like dead receive but its actually just being crushed. probably not your issue if its truly zero noise but worth ruling out i guess