VK6RMH VHF Repeater


Our very own VHF repeater is now on air and we are conducting tests on its range and identifying any signal black spots.

Tune to 146.850 MHz with .600 MHz -ve offset. The repeater also requires a sub tone of 91.5 to activate it.

A first cut diagram of how the mesh VOIP phone and Echolink computer are connected to the link transceiver at VK6MJ's QTH to provide those services to the repeater:

The diagram isn’t accurate - Martin has two audio mixer panels in the system, but I haven’t worked out how he’s got them connected yet.  Chris VK6XH is working on a nice diagram showing how it’s all connected together.  But in concept:
  • the link radio is on the repeater frequencies
  • audio out of the mesh phone is connected to the link radio’s transmitter - and also feeds the input to the Echolink computer - so mesh audio is heard on both the repeater and Echolink
  • audio out of Echolink is mixed with audio out of the link radio and fed into the mesh phone (so the mesh phone hears both Echolink and repeater audio)
  • the mesh phone is duplex (transmits and receives at the same time - the dotted arrow in the mesh box), so the receiver audio is also heard by both the mesh phone and Echolink (via the phone)

What isn’t shown is the push-to-talk arrangement to key up the link transceiver:
  • the Echolink computer has a PTT line that drives the link radio (unlike the duplex mesh phones (which transmit and receive together at the same time), Echolink works on a PTT arrangement where the user selects TX to transmit)
  • with no PTT, the output of the mesh phone instead drives a VOX - which also keys up the link transmitter when the mesh phone outputs sound
  • the VOX has a delay which holds the PTT keyed during sentences, and drops the PTT a second or so after the user stops talking
  • there may be an anti-VOX line that stops the VOX from triggering from the link radio’s audio feeding to the VOX through the mesh phone.
Chris Hiscox VK6XH is working on a better network diagram for the repeater and AllStar system.