Tried a multimeter with a built-in thermocouple on a King radio yesterday

Ngl, I grabbed it just to check continuity on a KX 155 and noticed the temp readout was showing 40 degrees higher than ambient. Turns out the fan relay in the cooling duct was stuck and the radio was about to cook itself. Anyone else use temp probes during routine avionics checks?

3 comments

3 Comments

josephbutler18d ago

Wait, a thermocouple saved you from a fried King radio? That's wild. I always just check for voltage and hope for the best.

the_charlie18d ago

Funny you mention that. I actually had a King radio start smoking on me back in 2018 because I didn't check the reference junction temp first. The thermocouple showed a 50 degree drift from ambient, and that was the only clue that the cold junction comp on the board was failing. If I'd just checked voltage like you're saying, I'd have fried the whole unit. Now I always meter both the thermocouple and the cold junction compensation resistor before I even power it up. Have you ever had a radio give you a false reading that led you down the wrong path?

faith68418d ago

Oh man, I gotta push back on this. Checking voltage first is way more practical than messing with thermocouples every time. You're adding an extra step that most people don't need. If the cold junction comp is failing, you'll see that in the voltage readings anyway once you know what to look for. I've been doing this for years and never had a radio smoke on me just because I skipped the thermocouple check. Sounds like that King radio had a deeper issue that voltage alone would've caught if you'd tested it right.