Yaesu System FUSION Configuration

Yaesu System FUSION Digital Capability on SVARC Repeaters

What Yaesu System FUSION Is

We're not necessarily best qualified to answer this, so we'll refer you to the vendor for their comprehensive page explaining what this is - http://systemfusion.yaesu.com/what-is-system-fusion/

SVARC's Yaesu System FUSION Repeater Configuration

In 2015, both the 2 meter and 70 centimeter repeaters were upgraded to Yaesu System FUSION DR-1X repeaters, enabling them to support 'digital' voice modes that leverage C4FM modulation techniques. These repeaters also support 'Automatic Mode Selection' (AMS), so that traditional analog FM can be used as well.

A Tale of Two Repeaters


There is a slight difference in how the two repeaters behave based on how they are configured -

  1. The 2 meter repeater is configured to fixed FM output signals regardless of whether it received  an FM (analog) or C4FM (digital) on the input receiver
  2. The 70 centimeter repeater is configured such that the transmitter output mode follows whichever modulation mode that the receiver is seeing at the input

Explaining What You May Be Hearing On The Air

This means that users of the 70 centimeter repeater gain the ability to use Yaesu System FUSION radios in a fully digital fashion through the repeater, end-to-end digital, while still allowing for analog FM users to use the repeater for analog conversations. Note the the repeater will select the mode at the beginning of each transmission, so the potential exists for each repeated transmission to be a different mode. On an FM-only, non Yaesu System FUSION capable radio, this could result in hearing a lot of what sounds like loud white noise when a digital signal opens the squelch of the rig.

Saving Your Hearing and Sanity

For this reason, FM analog-only users, particularly on the 70 centimeter repeater, may be best served to set their radio to use CTCSS / PL decode mode, in addition to the required CTCSS / PL tone encode mode. When the repeater is transmitting an FM analog signal, it is also configured to transmit the CTCSS / PL tone on the output. This way, FM-only users can use the receipt of the CTCSS / PL tone to selectively block when the squelch opens, and consequently, the noisy digital transmissions that do not incorporate the CTCSS / PL tone in transmission. This allows the user to still effectively monitor the 70 Centimeter repeater for FM analog calls, without all of the mind-numbing digital noise. Nearly all amateur radio equipment designed to operate on 70 centimeter FM modes built in the last 20 years support enabling tone decode features.

Something To Remember

The one potential downside to operating this way is that it becomes important to look at the rig before transmitting, and see if there are indications of an output from the repeater, even though the squelch isn't opening. The possibility exists that a digital call could be in progress, but nothing is being heard from the receiver (the desired case). Beyond the embarrassment of unwittingly causing interference by keying up on top of a QSO in progress, transmitting an analog FM signal on top of the digital QSO in progress can, in some cases, cause the repeater to lock up. When we say lock up, we mean that it won't recover without the repeater being powered off then back on again to recover normal operation. 

This secondary problem is widely thought to be a bug in the Yaesu System FUSION controller in the repeater that Yaesu has yet to successfully squash. The indications that the bug has been triggered include the repeater going into a state where it transmitting an unmodulated continuous carrier, and further input has no effect on it. 

Other anomalies have been observed triggering the problem, and we would ask that if you do find either of the SVARC repeaters in this locked-up state, that you attempt to reach us on the other repeater and let us know, so we can check it out and attempt to resolve it with remote power control to the repeater experiencing the lock-up.

Lastly, the SVARC repeater committee would ask that you please use and enjoy the repeaters, but that you exercise caution (and good operating practice) to check for the possibility of an on-going digital QSO on the 70 centimeter repeater before you attempt to key it up in FM mode.