I modified my Perseus SDR to have a much better
and stable frequency using an external GPSDO instead of the internal LO
For the propagation measurements I used for a very long time the internal Perseus clock oscillator
Performance off this oscillator was good enough as long as the temperature in the room is stable
During a search on the internet I found a publication from W7MLG: look here
At first I wanted to try and use this modification also but later decided not to follow his modification
In my opinion the modification from W7MLG was a bit overcomplicated
I do not quite see the need for an extra 80 MHz
reference Wenzel oscillator and I wanted to try
Also the input modification from W7MLG using a
balanced transformer to get a optimal connection to the AD converter.
This makes the modification less complicated and in my opinion there is no need to add an extra circuit board into the Perseus
First thing to do is do cut two small traces off the Perseus board to disable the original clock oscillator
In the first picture is shown the two traces of the original oscillator who are cut using a sharp knife
I then added two short wires, the first one on the left to
ground and the second on the right to the clock input
For the 80 MHz oscillator signal I am using a Bodnar GPSDO at
80 MHz at the lowest power setting
When the 80 MHz signal is switched off the Perseus software is
crashing and needs to be restarted after the 80 MHz is back on.
After setting up the system it is needed to clear the previous
frequency calibration from the Perseus to have a good frequency readout.
Not many Hams use the Perseus for very exact frequency
receiving but in my propagation measurements