Recently I had a problem with a Mitrek radio, The RX channel element would not reliably start oscillating on power-up. In my experimenting, I discovered that the problem related to the power supply I used.
I had four power sources - two linear supplies, one switcher, and a battery. One of the linears and the battery worked fine. The other linear and the switcher created the non-start problem. I finally noticed that the radio has two internal power sources for the channel element (9.5 Reg and 9.5 switched), and wondered if the timing of the two sources could be the problem. So I slowed down the 9.5 switched source, and that cured it. The channel element now starts every time from any of the power supplies. For those interested, I added a 100uF cap from the base of Q1 (the receiver 9.5V Switched supply) to ground. This slowed down the voltage output of the 9.5 switched source.
