Showing posts from February, 2021

A look into the RX-888 mkII

  The RX-888 mkII designed by Justin Peng and Howard Su  arrived!   It is an evolution of the first RX888. The curiosity won out and I opened it. Be careful if you decide to open your device because two heat pads are used to carry the heat from the R828D and the LTC2208 to the aluminium case. I managed to slide them out without damaging them by moving the PCB very gently. A plastic wide stick may help to push out the pads and after to reassemble the radio. The PCB layout is similar to RX888 In HF the input attenuator is a  PE4312   covering a 31.5 dB attenuation range. This replaces the 0, -10 ,-20 dB attenuator of RX888.  It is followed by the low pass filter at 64 MHz.  Then two switches PE4259   select the HF input or the VHF tuner R828D produced by Rafael Micro that replaces the R820T2. The added transformer connects in a balanced way to the R828D IF outputs. An AD8370  digitally controlled variable gain amplifier (VGA) provides precision gain control, high IP3, and low noise figur