Re: QCX 40
James Daldry W4JED
Your radio has 2 detectors working "in parallel", either one of which will do a good job of receiving signals. There are 2 detectors because by adding the detected signals 90 degrees out of phase one sideband is canceled out - signals are all on one side of zero beat. Like a "real" radio. The 3 controls are to adjust the phase of the audio signals to exactly 90 degrees. The fact that they do nothing suggests that one of the signals is missing. Since T1 has been removed the probable cause is that one of the "little" coils has a bad connection on it. IC4 should show the same voltage on pins 7 and 9, and should show equal resistance to ground with an ohmmeter.
On 09/06/2018 06:06 AM, Paul Harrison wrote: