Capacitor values?

[High Pressure]

Here's a possible solution to the problem with the problem.... If you would be satisfied with say a 10 sec delay before start up of the radar detector.. an r/c circuit can delay voltage supplied to the gate of the SCR... This would allow the main supply voltage to the SCR to be switched off when the ignition switch is turned to the off position...allowing reset of the SCR.

So a resistor, capacitor & SCR could be used...