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</o:shapelayout></xml><![endif]--></head><body lang=PT link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span lang=EN-US>SDR-4+ receiver released<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US>Recently while catching up with the waiting list for the SDR-4 general coverage receiver I've been investigating several new technology devices that have recently been released for use on 4G infrastructure. <o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US>One is a ultra high IP3 amplifier using E-PHEMT technology that was originally designed for high linearity amplifiers for LTE base station use. <o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US>The device has a claimed third order intercept (IP3) figure of 42 dBm. As a comparison the venerable 2N5109 transistor often used in many classic amateur radio designs for high performance RF amplifiers has a quoted manufacturer's IP3 figure of 35 dBm.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US>Obviously being a radio amateur the next stage was to try it in a SDR-4 receiver. The performance was much better than the existing power MOSFET RF amplifier and as the result of other minor changes that have been added to the receiver recently we have decided to release a new version of the receiver, the SDR-4+.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US>To sum up the changes over the earlier SDR-4 receiver:<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US>New ultra high IP3 E-PHEMT amplifier<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US>Revised gain distribution through the receiver<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US>Revised bias circuit for improved IQ balance<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US>Additional 3.5mm socket for IQ audio output<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US>Reduction in spurious low level tones seen on the SDR display.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US>Removal of the 10 MHz calibration oscillator<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US>The receiver is still powered from the 5V USB ports of a PC but it now takes more current to power the RF amplifier.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US>We have had to increase the price of the receiver to £169.95 ($266-82 or 204.28 Euros at the current rate) but I think that the increase in performance is well worth it.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US>More details on the web page:<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US>http://www.crosscountrywireless.net/sdr-4.htm<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US>Now an offer to all existing users of SDR-4 receivers...<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US>If you send your SDR-4 receiver back to us with the difference in price between the SDR-4 and the SDR-4+ and return shipping we will upgrade your receiver to the new SDR-4+ specification. That's £20 ($31.40 or 24 Euro) plus the cost of return shipping. I think it's worth doing, I've already upgraded all my receivers. This offer applies to all SDR-4 owners even if you bought the receiver secondhand.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US>One last thing... What's E-PHEMT stand for?<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US>Enhancement-mode pseudomorphic high-electron-mobility transistors<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><p class=MsoNormal>73,<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Chris, G4HYG<o:p></o:p></p></div></body></html>