test1

There are many circuit for making 90 degree phase shift on VHF. This IQ Oscillator is easy way with two logic IC's. 74AC04  inverter is used as oscillate circuit. C5 and R6 is phase shifter.74HC14 has a duty to convert into square-wave.

It is usualy used 74HCU04 in crystal oscillator circuit. Buffer of 74AC04 cause  parasitic oscillation. So I tested with 74HCU04 first,but the result was not good for me.

This circuit should work at the other frequency.You may change L1 and C18. If you use Q1 fundamental,L1 and C18 is no need.


proto typr reciver

It is difficult to reject image. C and R have little error tolerance each. The provided signal does not become 90 degrees precisely.

test2

I replace register to trimmer. C5 = 20pF VR = 200Ω.There became few images when I adjusted it carefully.