Amateur Radio

Possible Causes

• •Wrong CTCSS/PL tone
• •Offset incorrect
• •Insufficient power to reach repeater
• •Repeater offline

Diagnostic Steps

1. 1.Verify CTCSS tone matches repeater requirements — check local repeater directory
2. 2.Confirm offset direction and frequency (standard 2m offset is −600 kHz, 70cm is −5 MHz)
3. 3.Increase power output or relocate for better line of sight
4. 4.Try transmitting without tone to hear if repeater responds
5. 5.Check if repeater is listed as active on repeaterbook.com

Possible Causes

• •Microphone gain too high
• •ALC compressing audio excessively
• •Wrong mode selected
• •RF feedback into microphone

Diagnostic Steps

1. 1.Reduce microphone gain in radio menu
2. 2.Check ALC meter — should peak in the upper third, not peg continuously
3. 3.Verify correct mode — FM for VHF/UHF voice, USB for HF above 10 MHz
4. 4.Move microphone cable away from feedline to prevent RF feedback

Possible Causes

• •Antenna not cut to correct length
• •Ground system inadequate
• •Feedline has water ingress
• •Antenna too close to metal structures

Diagnostic Steps

1. 1.Measure antenna length and compare to calculated resonant length
2. 2.Check counterpoise or radial system for vertical antennas
3. 3.Inspect all coax connectors for moisture and corrosion
4. 4.Use antenna tuner to match on non-resonant frequencies
5. 5.Move antenna away from metal gutters, downspouts, and structures

Possible Causes

• •RF entering shack on power lines
• •Feedline radiating near equipment
• •Ground loop in audio cables
• •Operating near resonant frequency of audio cables

Diagnostic Steps

1. 1.Add ferrite cores to all cables entering shack — power, audio, USB
2. 2.Check that coax shield is properly grounded at single point
3. 3.Use balanced audio connections where possible
4. 4.Reduce power output temporarily to confirm RF is the cause