Troubleshooting & Repair

RFI Causes Fundamental overload – clean, but very strong signals Radio Frequency Interference Fundamental overload – clean, but very strong signals Harmonics Spurious Emissions

Curing your neighbor’s RFI First, make sure your station is operating properly If TVI – is your own TV receiving interference? Ideal next step is to identify nature of “aggressor” and “victim” – f, location, etc. Telephone – acts as radio receiver –add RF filter at telephone RF filters – Snap-on ferrite chokes; Lowpass, Highpass, Bandpass, &Band-reject filters

If your neighbor’s Part 15 devices interfere with you Work to identify offending device Politely inform him that rules require him to stop usage if RFI occurs Apply fixes at your station if practical

“Distorted or Noisy Audio” Off frequency Low batteries Bad location Hold radio “straight up”

“Garbled or Unintellegible Transmissions” RF Feedback FM: Over-deviation – talk farther away or, Under-deviation – speak up! Noise or whine on mobile unit: interference from vehicle’s electrical system

Multimeter or DMM Voltage: Voltmeter - connect in parallel Current: Ammeter – connect in series Resistance: Ohmmeter – unpowered target Capacitor with Ohmmeter – reads low, then high

Soldering Use Rosin-core solder Use correct size iron and tip Be able to see joint clearly Apply heat to terminal, apply solder to terminal

Soldering tools

Bad Solder Joint (Cold Joint) Photo http://www.aaroncake.net/

Bad Solder Joint (Cold Joint) Photo: Wikipedia

Broken and Good Joints Photo: Wikipedia