Beginning

Linrad is a very nice and interesting project. If you want to test an easy solution of SDR, Software Define Radios, this could be something for you.

The kit

The kit is available from KB9YIG, Tony. The version 7.0, that I have used, is originally thought for use on the 10m-band but can easily be modified. There are several different software available on the net and I recommend that you join the Yahoo-group “Softrock40” if you're interested in the Softrock!

Modification

Since the oscillator originally is intended for about 28MHz, I have changed the two capacitors, C4 and C5 in the schematic, to 220pF.
Changing frequency from 28MHz to 10,7MHz means also that the phasing-capacitor, C9, between the two OP-amplifiers must be changed. Tony recommended 100pF and this results in a quite good phasing between the two clock-signals for the switch-circuit. I think a little more can be done here with a trimmer in parallel with this 100pF capacitor.
The input filter must be modified. I have used 470pF for C23 and C25. The inductors in parallel with these two capacitors, L1 and T1, are made with 12 turns on the original cores. (T1 only at the input, output is still 8 turns bifilar.)
The mid inductor, L2, is also original core but with 25 turns. This was hard to get on the core so next time I will use thinner wire. C24 is calculated to 109pF. I have used a 100pF and a SMD 0805 10pF capacitor in parallel. This SMD capacitor is soldered on the soldering-side. Increasing from 100 to 110pF really raised the return-loss at the input.
Return-loss is measured to about 15-16dB with a R&S-instrument. Loss is about 1 to 1,5dB. For an IF-demodulator there is no point of trying to improve these figures.
This is how my first SoftRock looks like. The big black thing at the right is a ferrite for choking the audio-output.

SoftRock mounting in the FT225RD

Tony tells us that the mounting-holes are separated by 1.65 times 1.35 inches. This is 41.9 times 34.3 mm.