mitaux8030
Silent Key
Hi all,
some background to these pictures... this happened a long time ago.
Here in Tasmania (yes, it is a real place, and yes we really do have Tasmanian Devils, but they're nothing like the cartoon depicts - except maybe their eating manners!) the pace of life on this island is a little slow. Not a lot happens here.
We're seperated from the mainland of Australia by a body of water some 280 miles / 450 kilometres span.
Some local scanner enthusiasts knew that, occasionally, strong tropospheric ducting would carry VHF & UHF signals from the mainland of Australia across the water to Tasmania. The city of Melbourne (population approx 4 million) is just on the other side of the water, and so provides a lot of interesting listening compared to our local fare.
Along with a few other scanner enthusiasts, we decided to try a little experiment that - ah - got out of hand somewhat. At a nearby hilltop where I have a repeater located for a private two way radio network, we put up the following yagis, co-phased them using a Wilkinson combiner / divider of my own construction, and fed the lot inside the hut with Belden 9913 air-space coax. Inside, we had a very low noise 1.0dB NF preamp with bandpass filter, and then into a very hot receiver from a two way radio, scanning various UHF frequencies from the mainland - 280 mi / 450 km distant. We found that we didn't need any tropospheric ducting to recieve these signals at all with this setup !!
The co-phased yagis had a gain of approx 22dBd (going on manufacturers specifications) and from field measurements we did, that is pretty close to the mark. The preamp added a further 4dB of overall performance (not gain).
We even took it one step further by re-transmitting what was heard via a low power licence free frequency. Unsuspecting scanner users who stumbled upon the licence-free freq. couldn't understand / believe what was going on! hehe.
Sadly, this was all dismantled about 3 years ago, but it was a fun thing to try out.
some background to these pictures... this happened a long time ago.
Here in Tasmania (yes, it is a real place, and yes we really do have Tasmanian Devils, but they're nothing like the cartoon depicts - except maybe their eating manners!) the pace of life on this island is a little slow. Not a lot happens here.
We're seperated from the mainland of Australia by a body of water some 280 miles / 450 kilometres span.
Some local scanner enthusiasts knew that, occasionally, strong tropospheric ducting would carry VHF & UHF signals from the mainland of Australia across the water to Tasmania. The city of Melbourne (population approx 4 million) is just on the other side of the water, and so provides a lot of interesting listening compared to our local fare.
Along with a few other scanner enthusiasts, we decided to try a little experiment that - ah - got out of hand somewhat. At a nearby hilltop where I have a repeater located for a private two way radio network, we put up the following yagis, co-phased them using a Wilkinson combiner / divider of my own construction, and fed the lot inside the hut with Belden 9913 air-space coax. Inside, we had a very low noise 1.0dB NF preamp with bandpass filter, and then into a very hot receiver from a two way radio, scanning various UHF frequencies from the mainland - 280 mi / 450 km distant. We found that we didn't need any tropospheric ducting to recieve these signals at all with this setup !!
The co-phased yagis had a gain of approx 22dBd (going on manufacturers specifications) and from field measurements we did, that is pretty close to the mark. The preamp added a further 4dB of overall performance (not gain).
We even took it one step further by re-transmitting what was heard via a low power licence free frequency. Unsuspecting scanner users who stumbled upon the licence-free freq. couldn't understand / believe what was going on! hehe.
Sadly, this was all dismantled about 3 years ago, but it was a fun thing to try out.
