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VK4EA |
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VK4EA |
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My first foray into ATV was via a kind loan of FM 23cm transmitter loaned by Danny, VK4KI. This was after I attempted to build a 23cm FM transmitter consisting of modules from minikits.com.au for the Redcliffe & Districts Radio Club. Danny kindly assisted with getting the Club's transmitter going. And then I was hooked.
A 13cm.co.uk 23cm TX module was acquired, and a Minikits 23cm PA was constructed and assembled into a 2RU rack case. Some reasonable results, once the pre-emphasis was sorted out.
However, there was digital to explore. The BATC (batc.co.uk) organised a deal with AntennaAir for a frequency agile DVB-S transmitter module, bewdy! So again it was assembled into a 2RU enclosure with a 23cm PA and on air it goes.
My station looks a little like this, the transmitter is on the shelf to the right, next to the receiver.
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My station is managed using vMix, an awesome bit of gear. No need to buy an expensive video console. I've written up an article on vMix here.
I use the smaller Dell monitor on the right as my preview screen, all display devices are driven from a 4 output video controller. One HDMI port and the Dell monitor are cloned using the Windows feature, and the HDMI to composite converter connects to the transmitter. So everything I see on the Dell monitor is going to air (when the transmitter is powered up). The remaining DVI ports drive the large monitors.
For live transmissions from the shack, I use a Logitech webcam. This setup allowed me to anchor the VK4 portion of the Worldwide ATV QSO party - http://www.seqatv.org/2-uncategorised/22-worldwide-atv-qso-party
For receive I use a Strong SRT5430, manually programmable. Bought from Harvey Norman for $50, there are plenty of cheaper options, connected via HDMI to the Kogan TV mounted up high. I also have a free to air antenna connected so I can watch the footy downstairs :-) The STB also drives an EasyCap USB connected AV capture device, this is used by another PC that runs the Adobe LiveStreaming software for the BATC streamer. The VK4RMG stream is available at this link.
Finally I've managed to get a 9600 baud APRS iGate going. It's only 3/4 of a Watt into an antenna under the house at the moment, running UView32 gating eveything in a 500 km radius to 439.100 MHz. Object is VK4EA-2.
Equipment is an Argent Data T3-9670, they do have an acknowledged issue with decoding from a number of TNCs, however everything should be qble to decode its transmitted packets. My VX8 and the TM-D710 in the car decodes it all, in the next few weeks I'll get an antenna up. If it gets used, I'll think about an iGate located on a hill behind Caboolture, and a digi at Oceanview. All depends whether I get motivated to interface the iGate radio/TNC to a Raspberry PI running APRSX. And if there is sufficient interest in 9600 APRS?
An evolving project.
Capability
Antennas
Wish list
Kuhne G3
Initially this station consisted of a VK3XDK transverter, I'd be buggered if I could get any decent sensitivity. My construction technique was not up to it. So I admitted defeat and bought a Kuhne G3 (432MHz IF) and it's companion local oscillator with a 10MHz ref input.
It could not get any easier other than getting someone to build it for you. A 2RU 19" enclosure houses the transverter, LO, changeover relay. Front metering provides an indication of output RF power, which is available direct from the transverter. Additionally I setup an ammeter to indicate the draw from the 12V supply. Front panel connections are a BNC for the 10MHz, and a BNC for the 432 MHz IF, and an RCA for the PTT. The rear simply has a SMA for the RF out.
Future plans are to complete the DEMI 3W PA, and install the Kuhne LNA.
For the antenna, I use a Directive Systems dual band feed horn, into a 1.2m fibreglass dish. The dish size makes up for the lack of a PA.
