HF FM Tests


Way back in the 1980s, WARG ran a series of tests, in conjunction with the WIA VK6 news broadcast, using FM (Frequency modulation) on HF to re-broadcast the VK6 WIA news. The transmitter used was a Yesua FT-757GX, which could run at 100 watts continuous carrier on FM.

FT-757GX used for VK6WIA FM news tests on HF

The results were outstanding with clear noise free FM broadcasts being received around the state. The frequencies tried were
  • 160 metres
  • 80 metres
  • 40 metres
Two main sites were tried as the broadcast site and these were Tic Hill and Busselton. In conjunction with the tests, several WARG members traveled to various locations during the weekends that the tests were run.

The tests took place when propagation was good during the 11 year Sun spot cycle and signals were remarkable on 80 metres out to about 300 kilometres. On 40 metres good noise free signals with FM quality could be received out to 1000 kilometres.

Driving around Kalbarri the VK6WIA news could be received in the mobile noise free.

VK6RBN 80M antenna
VK6RBN with 80 metre antenna for VK6 WIA HF FM Broadcasts

The tests were a great success and it showed that FM on HF works well when the correct band is chosen to cover a given area. Unfortunately no permanent FM broadcast on HF resulted from the experiments.