Yes, that should work, just switch the sub receiver antenna over to the main receiver to calibrate the phase. I think you'd get the best accuracy by looking for a null and then subtracting 180 degrees.
By the way, I think rather than an adjustable delay between the two channels you need an adjustable phase. (If the phases of the two local oscillators in the K3 differ by X degrees, than all audio frequencies also differ by X degrees.) There are a number of ways to do that, but probably the most straightforward is to re-convert each audio signal to "RF" (a few kHz) using local oscillators of the same frequency but different phases, and then convert back to baseband with a single LO. That could be done either with hardware or in software. Just a SMOP. (Small matter of programming :=) Alan N1AL On Thu, 2010-09-16 at 10:08 -0700, David Gilbert wrote: > Thanks for the reply, Alan. > > That's interesting. I didn't realize that the two receivers in the K3 > had a random phase difference between them even when locked. I noticed > differences in phase delay when I changed frequencies during my tests > with the two horizontal antennas on the tower, but I mostly attributed > that to different arrival angles for the different stations being > monitored, and different phase delay of the feed lines (expressed in > wavelengths) at the new frequencies. > > However, that random phase difference between the two receivers could be > adjusted out by momentarily feeding the same antenna into both receivers > at each new frequency. That routing could be accomplished within the K3 > if there was a quick and easy way to control whether or not the sub > receiver was switched to the AUX RF antenna when diversity mode is > active. If that routing option took the form of a command, the whole > process could be done in software (either external or internal to the > K3) each time the frequency was changed ... albeit of course with some > settling delay while the phase difference was determined and adjusted out. > > 73, > Dave AB7E > > > > > On 9/16/2010 8:42 AM, Alan Bloom wrote: > > Yes, I think that would work fine. There are two issues that I can > > think of: While the main and sub receivers are phase-coherent, the > > actual phase difference between them is random. I believe that if you > > change frequency it is not guaranteed that the phase difference will > > be the same. So every time you change frequency you may have to > > re-adjust the phase delay to get the antenna to "point" in the right > > direction. > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[email protected] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
