Information on Simplex Links
Set-up and configuration of an Echolink Simplex node
A Simplex Link (Figure 2) is an analog VHF or UHF transceiver (HT, mobile, or base) configured to provides the Sysop and local users full RF access to the Echolink network when no repeater is available. The basic configuration consists of a radio;
- Configured in simplex mode (no +/- shift on transmit)
- Tuned to a simplex frequency (i.e. 146.500 MHz)
- Connected via a compatible radio-to-PC interface (same as used for transmitting digital modes) to an Internet connected computer (desktop, laptop, RaspberryPi, tablet, etc.) running Echolink (or compatible variant) software in Sysop mode
- Both Tone Squelch Encode and Decode are enabled (prevents non-RF signals from inadvertantly keying radio)
Often, older used mobile or inexpensive handheld units are employed, but there are new rigs available with Echolink capability built in. Simplex links are also a great way for a user who may not be within HT range of a local repeater, to stay connected in and around their property. A number of users have deployed one radio as the link, and a dual VHF/UHF cross-band capable radio to act as the link between their HT and the Simplex Node.
PROS: Very simple to implement, minimal equipment investment, portable, call sign ID announcements only broadcast locally. Simplex Links can quickly become Remote Repeater Links by simply reconfiguring the radio to access a local non-Echolink enabled repeater and a making a few minor changes to the settings in the software
CONS: Tends to be short range and requires higher power output, 100% duty mode requires additional cooling for transceivers, antenna height is critical, primarily operated in VOX - "Voice Operated Xmitter" (transmitter) - mode (COR - "Carrier Operated Relay" - mode keying is preferred, but more complicated).