KD5TFD Station: SDR-1000, VK6APH's QSD T/R Switching mod

Some quick pictures of my implementation of VK6APH's suggested mod to get rid of the noise spike into the sound card when going from transmit to receive.

Plase note ... the picture above shows an incorrect connection - the red wire going to pin 2 of T1 needs to go to pin 5

The picture below is a picture of the daughterboard while it was being assembled. This gives some idea of the size of the parts. Actually this size part is not too bad to work with, it's one of the larger surface mount packages.

It may not look pretty but seems to work quite well. Mod was done by mounting an FST3126 on a suface mount prototyping board and pulling the needed signals from vias on the TRX board. Only the VCC/2 signal could not be found at a via, so it was pulled from pin 2 of T1. The little board sits up on the wires and floats above the board on the wires grabbing signals from the TRX board.

I believe a PC board is being developed by some of the other SDR-1000 users, it would be a bit cleaner to install than this. It will also have provision for adding capacitors to parallel with the existing QSD caps to tweak up the bandwidth of the QSD a bit.

Comments to: Bill Tracey (kd5tfd@ewjt.com)

Last Updated: 28 Feb 2005

Copyright © Bill Tracey 2005