Build and fix a simplex node
The parts you need, the software, the network setup and fixes for the most common audio problems.
A node on GMRS frequencies needs a license. Start with the legal checklist and the setup checklist.
Parts list
Radio
A GMRS-capable radio that can key on command. Handhelds work for a small node. A mobile radio gives more power and a steadier signal.
Small computer
A single-board computer or a spare mini PC runs the node software and connects to the internet.
Sound adapter
A USB audio adapter built for radio use carries audio and the push-to-talk signal between the computer and the radio.
Radio cable
A cable that joins the radio's mic and speaker jack to the adapter.
Antenna and coax
A good outdoor antenna as high as you can safely put it, with short, quality coax.
Power supply
A stable power source. Many nodes also add a battery backup for outages.
Internet
A wired connection is steadiest. Wi-Fi works but can drop.
Software
AllStarLink
Free software that links nodes over the internet. It is the most common choice for amateur and GMRS nodes.
ASL3
The current generation of AllStarLink software, built for modern operating systems.
Hotspot units
Ready-made devices with the software already loaded. Faster to start, less to tinker with.
Network setup
Register your node
Create an account with the node network and get a node number.
Open the right port
AllStar uses UDP port 4569 for linking. Forward it on your router to the node, or use a service that avoids the need.
Use a fixed address
Give the node a reserved address in your router so the forwarding keeps working.
Keep the system updated
Install updates and use strong passwords. A node is a computer on your network.
Fixing common problems
- Voices sound distorted
- Lower the audio input level or the radio's volume. Overdriven audio is the top cause.
- The node transmits stuck on
- Check the push-to-talk wiring and the timeout timer. Power cycle the adapter.
- You hear an echo
- Both ends are looping audio. Check for two nodes connected in a ring.
- Others cannot hear you
- Raise the transmit level slightly and check the PL tone and frequency.
- Cannot connect to other nodes
- Verify the router port forward, the internet link and your node number.
- Audio cuts off early
- The squelch is too tight or the signal is weak. Adjust squelch and the antenna.