so this has been bugging me for a couple weeks now. my 7300 was running fine and then one day i noticed the output was way down, like im getting maybe 20-25w max on HF where i should be seeing close to 100. the ALC looks normal on the display and the radio doesnt throw any error codes or anything. SWR on the dummy load is flat so its not an antenna issue.

i already checked the obvious stuff, power supply voltage is solid at 13.8v under load, no weird smells from the radio, fans seem fine. TX audio sounds normal on a monitor receiver, no distortion or anything. its just the power thats wrong. i was wondering if anyone has seen this before — bad finals maybe? or could it be something in the driver stage? i dont want to just throw parts at it without at least having some idea where to look first.

the radio is about 4 years old, not under warranty anymore obviously. i do have a service manual so i can poke around if someone can point me in the right direction

seen this exact thing on a buddys 7300 last year. turned out to be one of the final transistors (RD100HHF1) had partially failed — not fully dead but limping along. what gave it away was the drain current was uneven between the two devices when measured individually. if you have a way to do RF power measurements on each side of the push-pull output you might find one is pulling more than the other.

that said before you go digging into the finals its worth checking the PA bias voltage. there's an adjustment trimmer for it and sometimes they drift, especially if the radio has seen any heat stress. get into the service manual and find the bias adjustment procedure — its not hard and if the bias is low that would absolutely explain reduced output without any fault codes. try that first before assuming its a blown transistor because replacing those finals is doable but kind of a pain with all the thermal compound and torque specs.

dont overlook the lpf relays either. i had a radio doing something similar and one of the low pass filter switching relays had corroded contacts and wasnt fully switching. it was passing signal but with enough loss to tank the output. kind of an annoying one to find because everything looks okay at a glance. you can sometimes hear a weak or slow click on that relay if you listen close while switching bands — or just probe across the contacts with a meter in resistance mode while the relay is energized. anyway just throwing that out there because the finals get blamed for everything and sometimes its something dumb upstream