1. Troubleshooting & Repair

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

3. 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

4. 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

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

6. “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

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

8. 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

9. Soldering tools

10. Bad Solder Joint (Cold Joint)
Photo

11. Bad Solder Joint (Cold Joint)
Photo: Wikipedia

12. Broken and Good Joints
Photo: Wikipedia