ARLA/CLUSTER: Novo SDR-4+ usa infraestruturas 4G

[João Gonçalves Costa]

SDR-4+ receiver released

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.

One is a ultra high IP3 amplifier using E-PHEMT technology that was originally designed for high linearity amplifiers for LTE base station use.

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.

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+.

To sum up the changes over the earlier SDR-4 receiver:

New ultra high IP3 E-PHEMT amplifier

Revised gain distribution through the receiver

Revised bias circuit for improved IQ balance

Additional 3.5mm socket for IQ audio output

Reduction in spurious low level tones seen on the SDR display.

Removal of the 10 MHz calibration oscillator

The receiver is still powered from the 5V USB ports of a PC but it now takes more current to power the RF amplifier.

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.

More details on the web page:
http://www.crosscountrywireless.net/sdr-4.htm

Now an offer to all existing users of SDR-4 receivers...

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.

One last thing... What's E-PHEMT stand for?

Enhancement-mode pseudomorphic high-electron-mobility transistors

73,

Chris, G4HYG
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