Software Defined Radio
Two Metre SDR
I've been playing with SDR for a while now. Firstly using Softrocks but now I have moved on to my own concoctions. Here is a video of Rocky software receiving some two metre beacons via my two metre hardware. This was taken under flat band conditions. I'm not saying it's more sensitive than a conventional radio but what a great way to check conditions!
Sorry about the low volume.
VHF Hardware
The Two Metre SDR hardware consists of two Minicircuits ADE1 smd diode ring mixers, a resistive power divider and low pass filter phase shifter, a couple of op-amps and sdr-kits.net wonderful usb snyth. It will also transmit. At the moment, August 2010, I can get about a watt or so out of the hardware and use this to drive a Mirage amplifier to 50 watts.
The hardware has been up and running for over a year now and DX has been worked on tropo and Sporadic E. The spectrum display of nearly 100kHz is really a great advantage during an E's opening as you are able to spot new DX stations as soon as the appear on the band.
Diagram of the mixer and phase shifter.
It is simple really little more than a transverter thanks to sdr-kits synth.
HF - VHF SDR
This is based on the design by WB6DHW. I purchased a board from David, placed the mixer and flip-flops on it but the rest of the hardware is external to that board. A small 20W PA with band pass filtering allows operation on HF, Four Metres and Six.
It is all still work in progress.
